Devices and techniques for a posterior lateral disc space approach

ABSTRACT

This invention relates to devices and instruments for implant insertion through a posterior lateral opening to the disc space. The instruments include an implant inserter, and the devices include a spinal fusion implant engageable by the implant inserter. The implant provides bilateral support of the adjacent vertebrae when inserted into the disc space from a postero-lateral approach.

CROSS-REFERENCE TO RELATED APPLICATIONS:

The present application is a continuation-in-part of patent applicationSer. No. 09/858,197 filed May 15, 2001 now U.S. Pat. No. 6,764,491,which is a continuation-in-part of U.S. patent application Ser. No.09/694,521, filed on Oct. 23, 2000 now U.S. Pat. No. 6,830,570, whichclaims the benefit of the filing date of Provisional Application No.60/160,667, filed Oct. 21, 1999.

BACKGROUND OF THE INVENTION

The present invention relates to techniques for use in interbody fusionprocedures, instruments for performing such procedures, and implantsinsertable in the spinal disc space. More specifically, but notexclusively, the present invention relates to implants, methods andinstruments for use in a posterior lateral approach to the disc space,including a transforaminal approach.

Normally intervertebral discs, which are located between endplates ofadjacent vertebrae, stabilize the spine and distribute forces betweenthe vertebrae and cushion vertebral bodies. The spinal discs may bedisplaced or damaged due to trauma, disease or aging. A herniated orruptured annulus fibrosis may result in nerve damage, pain, numbness,muscle weakness, and even paralysis. Furthermore, as a result of thenormal aging processes, discs dehydrate and harden, thereby reducing thedisc space height and producing instability of the spine and decreasedmobility. Most typically surgical correction of a collapsed disc spaceincludes a discectomy (surgical removal of a portion or the entireintervertebral disc). The discectomy is often followed by restoration ofnormal disc space height and bony fusion of the adjacent vertebrae tomaintain the disc space height.

Access to a damaged disc space may be accomplished from severalapproaches to the spine. One approach is to gain access to the anteriorportion of the spine through a patient's abdomen. However, extensivevessel retraction is often required and many vertebral levels are notreadily accessible from this approach. A posterior approach may also beutilized. However, this typically requires that both sides of the discspace on either side of the spinal cord be surgically exposed. This mayrequire a substantial incision or multiple access locations, as well asextensive retraction of the spinal cord. To alleviate problemsassociated with both anterior and posterior approaches to the spine, aposterior lateral approach, such as a transforaminal approach, to thedisc space may be utilized. While it is desirable to place one or moreimplants in the disc space so that the load of the spinal column isevenly distributed, accurate placement of implants in the disc spacefrom a single posterior lateral approach has heretofore been extremelydifficult. Thus, this approach to the spine is seldom used in practice.

Therefore, there remains a need for improved instruments, implants andtechniques for use in a posterior lateral approach to the disc spacethat allows unilateral disc space preparation and implant insertion toprovide bilateral stability to the subject disc space.

SUMMARY OF THE INVENTION

The present invention provides implants, instruments and methodsparticularly adapted for disc space preparation and implant insertionfrom a posterior lateral approach to the disc space.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a lamina spreader according to thepresent invention.

FIG. 2 is a perspective view of the lamina spreader of FIG. 1 with thehandle portions rotated to a folded position.

FIG. 3 is an elevational view of a spinal column segment showing thedistal portion of the lamina spreader of FIG. 1 engaged to the lamina oneither side of a disc space.

FIG. 4 is a perspective view of a disc space spreader according to thepresent invention.

FIG. 4( a) is a plan view of the distal end of an alternate embodimentdisc space spreader.

FIGS. 5( a) and 5(b) are perspective views of the disc space spreader ofFIG. 4 with a lever arm and a perspective view of the lever arm,respectively.

FIG. 6 shows the sequence of the insertion of the disc space spreader ofFIG. 4 into a disc space.

FIG. 7 is a perspective view of a distractor according to the presentinvention.

FIG. 8 is a perspective view of an alternative distractor havingapplication in the present invention.

FIG. 9 is a top plan view of a vertebra with the distractor of FIG. 7inserted in the disc space.

FIG. 10 is a perspective view of a straight reamer according to thepresent invention having the outer shaft partially cut-away to show theinner shaft.

FIG. 11 is a perspective view of a curved reamer according to thepresent invention having the outer shaft partially cut-away to show theinner shaft.

FIG. 12 is an end view of the reamer cutting head used with the reamersof FIGS. 10 and 11.

FIG. 13 is a top plan view of a vertebra with the straight reamer ofFIG. 10 inserted in the disc space.

FIG. 14 is a top plan view of a vertebra with the curved reamer of FIG.11 inserted in the disc space.

FIG. 15 is a perspective view of a guided rotary cutter according to thepresent invention.

FIG. 16 is an enlarged view of the distal end portion of the cutter ofFIG. 15.

FIG. 17 is a top plan view of a vertebra with the cutter of FIG. 15inserted in the disc space.

FIG. 18 is a perspective view of a guided rotary cutting tool accordingto the present invention.

FIG. 19 is an enlarged perspective view of the distal end portion of thecutting tool of FIG. 18.

FIG. 20 is a top plan view of a vertebra with the cutting tool of FIG.18 in the disc space.

FIG. 21 is a perspective view of an alternative cutting tool head.

FIG. 22 is a further perspective view of the cutting tool head of FIG.21.

FIG. 23 is a perspective view of a push scraper according to the presentinvention.

FIG. 23( a) is section view taken through line 23(a)—23(a) of FIG. 23.

FIG. 24 is a perspective view of a pull scraper according to the presentinvention.

FIG. 24( a) is section view taken through line 24(a)—24(a) of FIG. 24.

FIG. 25 is a top plan view of a vertebra with the push scraper of FIG.23.

FIG. 26 is a top plan view of a vertebra with the pull scraper of FIG.24.

FIG. 27 is a perspective view of a straight chisel according to thepresent invention.

FIG. 28 is a lateral elevational view of a spinal column segment withthe chisel of FIG. 27 inserted in the disc space.

FIG. 29 is a posterior elevational view of a spinal column segmentshowing the disc space entrance created by the chisel of FIG. 27.

FIG. 30 is a perspective view of an alternate embodiment guided chiselaccording to the present invention.

FIG. 31 is an enlarged perspective view of the chisel head and shaftwith the chisel head in the position of FIG. 30.

FIG. 32 is a top plan view of a vertebra with the chisel of FIG. 30.

FIG. 33 is a perspective view an implant sizing guide according to oneaspect of the present invention.

FIG. 34 is the implant sizing guide of FIG. 33 with the handle detached.

FIG. 35 shows a perspective view of an implant insertion guide accordingto the present invention.

FIG. 35( a) is an enlarged view of the distal end portion of the implantinsertion guide of FIG. 35.

FIG. 36 is a perspective view of a straight implant inserter accordingto the present invention having the outer shaft partially cut-away toshow the inner shaft.

FIG. 37 is a perspective view of a curved implant inserter according tothe present invention having the outer shaft partially cut-away to showthe inner shaft.

FIG. 38 is a perspective view of an impaction tool according to thepresent invention.

FIG. 39 is a top plan view of the disc space showing the sequence of thecurved inserter of FIG. 37 inserting an implant into the disc space.

FIG. 40 is a perspective view of an alternate embodiment guided implantinserter according to the present invention.

FIG. 41 is an enlarged perspective view of the distal portion of theimplant inserter of FIG. 40.

FIG. 42 is an enlarged plan view of the distal portion of the implantinserter of FIG. 40 and an implant.

FIG. 43 is the view of FIG. 42 showing the implant and insertion toolmoved distally along the guide shaft.

FIG. 44 is a top plan view of a vertebra with the implant inserter ofFIG. 40 in the disc space.

FIG. 45 is a top plan view of a vertebra with an implant inserted intothe distal portion of the disc space.

FIG. 46 is a top plan view of a vertebra with a pair of implantsbi-laterally positioned in the disc space to provide bi-lateral supportto the spinal column segment.

FIG. 47 is a top plan view of a vertebra with a single implantpositioned in the disc space to provide bi-lateral support to the spinalcolumn segment.

FIG. 48 is a perspective view of an alternate embodiment implantinserter.

FIG. 49 is a perspective view of a still a further embodiment of animplant inserter.

FIG. 50 is a plan view of an intradiscal rasp according to anotheraspect of the present invention.

FIG. 50( a) is an enlarged view of an alternate embodiment head for theintradiscal rasp of FIG. 50.

FIG. 51 is a side elevational view of the intradiscal rasp of FIG. 50.

FIG. 51( a) is an elevational view of the head of FIG. 50( a) looking inthe direction of arrows 51(a)—51(a).

FIG. 52 is a top plan view of an implant and instrument set forinserting the implant into the disc space.

FIG. 53 is a top plan view of the implant and instrument set of FIG. 52with the implant partially inserted in the disc space.

FIG. 54 is an end elevational view of an implant according to anotheraspect of the present invention.

FIG. 55 is a top plan view of the implant of FIG. 54.

FIG. 56 is a perspective of the implant of FIG. 54 oriented towards theposterior face.

FIG. 57 is another perspective view of the implant of FIG. 54 orientedtowards the anterior face.

FIG. 58 is an elevational view of the implant of FIG. 54 looking towardsthe posterior face.

FIG. 59 is a perspective view looking toward the posterior wall ofanother embodiment implant of the present invention.

FIG. 60 is a perspective view looking toward the anterior wall of theimplant of FIG. 59.

FIG. 61 is an elevation view looking at the posterior wall of theimplant of FIG. 59.

FIG. 62 is an elevation view looking at the anterior wall of the implantof FIG. 59.

FIG. 63 is a plan view of the plant of FIG. 59.

FIG. 64 is an end elevation view of the implant of FIG. 59.

FIG. 65 is a sectional plan view of another embodiment implant insertioninstrument according to the present invention engaged to the implant ofFIG. 59, the sectional view illustrating first and second positions of aproximal portion of the implant insertion instrument.

FIG. 65 a is a perspective view of a pusher instrument.

FIG. 66 is an enlarged sectional plan view of the implant insertioninstrument and implant of FIG. 65.

FIG. 67 is a side elevation view of the implant insertion instrument andimplant of FIG. 65.

FIG. 68 is an enlarged plan view of the implant insertion instrument andimplant of FIG. 65 prior to engaging the implant to the implantinsertion instrument.

FIG. 69 is an enlarged plan view of the implant insertion instrument andimplant of FIG. 65 after engagement of the implant to the implantinsertion instrument.

FIG. 70 is a partial elevation view the proximal portion of anotherembodiment inserter instrument and alignment instrument.

FIG. 71 is a section view through line 71—71 of FIG. 70 showing theattachment of the alignment instrument to the proximal portion of theinserter instrument.

FIG. 72 is an enlarged section view shown an alternate connectionarrangement between the proximal portion and the implant engagingportion of the insertion instrument of FIG. 65.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of thepresent invention, reference will now be made to the embodimentsillustrated in the drawings, and specific language will be used todescribe the same. It will nevertheless be understood that no limitationof the scope of the invention is intended thereby. Any alterations andfurther modification in the described processes, systems, or devices,and any further applications of the principles of the invention asdescribed herein are contemplated as would normally occur to one skilledin the art to which the invention relates.

In a posterior lateral approach to the disc space, such as is providedwith a transforaminal approach, it is often difficult to prepare theproper locations in the disc space to receive an implant. Theinstruments and techniques of the present invention provide for improvedunilateral disc space preparation in both the distal and proximalportions of the disc space through a single opening. Another difficultyin posterior lateral approaches to the disc space is related to theproper positioning of the implant in the portion of the disc space mostdistal from the posterior lateral opening. While it is desirable thatthe implant be positioned in the distal portion of the disc space, it isoften too difficult to move the implant across the disc space to thedistal portion. Thus, the present invention further provides implantinserters, implant templates, implant insertion guides, and implantsthat facilitate implant positioning in the distal and proximal portionsof the disc from a posterior lateral approach.

Referring now to FIG. 1, there is provided a lamina spreader 500according to one aspect of the present invention. Lamina spreader 500includes a first arm 502 pivotally joined to a second arm 504 by pin506. Arms 502, 504 extend generally along a central axis 501 when in afirst spreading position. Extending distally from pin 506 are distalportions 515 and 516 of arms 502 and 504, respectively. Distal portions515 and 516 include lamina engaging portions 508 and 510, respectively.Lamina engaging portions 508 and 510 are generally U-shaped andconfigured to engage the lamina of an upper vertebra V2 and the laminaof a lower vertebra V1, respectively, on either side of the subject discspace, as shown in FIG. 3. Spreading portion 508 includes an outerportion 508 a configured to reside on the outer side of the laminaconnected to an inner portion 508 b configured to reside on the innerside of the lamina. Spreading portion 510 similarly includes an outerportion 510 a configured to reside on the outer side of the laminaconnected to an inner portion 510 b configured to reside on the innerside of the lamina.

The lamina can be spread by the surgeon grasping handle 502 a of arm 502and handle 504 a of arm 504, and forcing arms 502, 504 towards oneanother in the direction towards axis 501. There is also provided amechanism to force and/or maintain spreading portions 508 and 510 apart.The spreading mechanism includes an externally threaded rod 512threadingly engaged to branch 502 and a hand nut 514 received on rod512. Arms 502 and 504 may be forced together by action of threading nut514 to force rod 512 into threaded opening 503 in arm 502, therebyforcing spreading portions 508 and 510 apart and separating the laminato open access to the disc space. Nut 514 can also be used to thread rod512 into opening 503 after manually spreading the lamina via handles 502a, 504 a, until nut 514 contacts arm 504 to maintain the engagingportions 508, 510 in a spread condition.

In a preferred form, arm 502 has handle portion 502 a that is hinged torotate with respect to a non-rotating portion 502 b about a pin 516, andarm 504 has handle portion 504 a hinged to rotate with respect to anon-rotating portion 504 b about a pin 518. A first spring loadedlocking mechanism 520 resides in cut-out 524 formed in handle portion502 a, and a second spring loaded locking mechanism 522 resides in asimilar cut-out (not shown) formed in handle portion 504 a. Lockingmechanism 520 includes a finger 528 spring-biased into notch 530 formedin non-rotating portion 502 b. The surgeon or attendant can releasehandle portion 502 a by pulling proximally on grasping portion 532 topull finger 528 out of notch 530, and then rotate handle portion 502 atransversely to axis 501 about pin 516 to a position oriented about 90degrees with respect to non-rotating portion 502 b. Similarly, lockingmechanism 522 includes a finger spring-biased into a notch formed innon-rotating portion 504 b. The surgeon or attendant can release handleportion 504 a by pulling proximally on grasping portion 534 to pull thefinger out of the notch, and then rotate handle portion 504 atransversely to axis 501 about pin 518 to a position oriented about 90degrees with respect to non-rotating portion 504 b. Rotating handleportions 502 a, 504 a moves this portion of lamina spreader out of theway of the surgeon and avoids interference with other instruments to beinserted in the disc space.

It is contemplated that spreader 500 can be used to assist the surgeonin gaining access to the disc space. The rotating handles allow laminaspreader 500 to remain in place during subsequent procedures. It isfurther contemplated that the surgeon may not desire to use laminaspreader 500, and therefore proceed with disc space distraction aftergaining access to the disc space.

Referring to FIG. 4 and FIGS. 5( a) and 5(b), a disc space spreaderaccording to the present invention is shown. Disc space spreader 70 hasa proximal portion that includes a first branch 72 pivotally joined to asecond branch 74 by pin 76. Extending distally from pin 76 are distalportions 85 and 86 of branches 72 and 74, respectively. Distal portions85 and 86 have a distal working end that includes spreading portions 80and 78 that contact the endplates of the adjacent vertebrae to apply adistraction force thereto. Distal portions 85 and 86 further includelateral offset portions 81 and 79, respectively, that laterally offsetthe branches 72, 74 from the spreading portions 80, 78. Offset portions79 and 81 have a straight portion extending generally parallel tocentral axis 88 extending between branches 72, 74 and a bend forming afirst offset angle A2 with axis 88. Spreading portions 78 and 80 form asecond overall offset angle A21 with axis 88. In a preferred embodiment,offset angle A2 is about 120 degrees, but it is contemplated that offsetangle A2 can range from 90 degrees to 160 degrees. Offset angle A21 isabout 110 degrees. The offset portions 79, 81 laterally offset branches72, 74 from spreading portions 78, 80, allowing branches 72, 74 to befurther pivoted across the spinous process S, as shown by disc spacespreader 70 in FIG. 6, than would be possible without offset portions79, 81. In one form, the lateral offset distance d between axis 88 andthe center of the straight portion is between 10 to 20 millimeters. Thisallows the distal tip of spreader 70 to be properly oriented intoposterior lateral opening 35 formed in disc space D1.

To separate spreading portions 78, 80 a force can be applied to theproximal ends of branches 72, 74. In a preferred embodiment, disc spacespreader 70 includes a mechanism to force and/or maintain the separationof spreading portions 78 and 80. The spreading mechanism includes anexternally threaded rod 82 pivotally joined to branch 72 andpositionable in notch 83 formed in the proximal end of branch 74. Thespreading mechanism has an internally threaded hand nut 84 threadedlyreceived on rod 82. Branches 72 and 74 may be forced together by actionof internally threaded nut 84 on branch 74 forcing it towards branch 72,thereby forcing spreading portions 78 and 80 apart. A spring blade 89attached to branches 72, 74 biases branches 72, 74 apart.

Branches 72 and 74 also define opposing grooves 92 and 94 adjacent pin76. A lever arm or pusher 90 may be provided having an elongated shaft96 with a handle 98 on one end and an opposing spreader engaging portion99. Engaging portion 99 is configured for removable engagement withopposing grooves 92 and 94 formed in branches 72 and 74, respectively.In se, removal of bony structures to gain access to the disc space andresection of disc material may be conducted by known methods. As shownin FIG. 6, the distal end of spreader 70 is positioned at opening 35,and pusher 90 can be used to provide a pushing force in the direction ofarrow P into the disc space during the steps of inserting the spreadingportions 78 and 80 into opening 35. Disc space spreader 70 is pivotedsequentially in the direction of arrow R about spinous process S via theproximal end of branches 72, 74. This pivotal and distal movement fromproximal portion 41 to distal portion 37 of disc space D1 is indicatedby the relative sequential positions of spreader 70, 70′, 70″, and 70′″and spreader portions 78, 78′, 78″, and 78′″. Thus, branches 72, 74 andpusher 90 enable the surgeon to have simultaneous two-handed control ofspreader 70, with one hand controlling insertion movement with pusher 90and the other hand controlling pivotal movement with branches 72, 74.This positions spreading portions 78, 80 across the disc space, andprovides uniform disc space distraction so that the vertebral endplateswill be parallel when distracted. The location of spreading portions 78,80 in the disc space may be checked by any known visualizationtechniques before proceeding to tissue removal.

It should be understood that pusher 90 is engaged to disc space spreader70 during the steps indicated by spreaders 70′, 70″ and 70′″, but is notshown for purposes of clarity. The S-shaped connecting portions 79, 81provide a lateral offset to branches 72, 74 to laterally offset branches72, 74 from spreader portions 78, 80. This allows branches 72, 74 ofdisc space spreader 70 to avoid interference with the spinous process Swhen inserting the distal portions spreader portions 78, 80 throughopening 35 into disc space D1. Enlarged stops (not shown) can be formedon distal portions 85 and 86 in order to engage the adjacent vertebraduring insertion and limit advancement of spreaders 78 and 80 into discspace D1. After the spreader is inserted into the disc space, lever arm90 may be removed.

Disc space spreader 70 is manipulated as described above to spread ordistract disc space D1 to the desired height. In one procedure, it iscontemplated that lamina spreader 500 is first used to spread thelamina. Since this tends to tilt the disc space and make the vertebralendplates non-parallel, spreader 70 can then be used to distract thedistal portion of the disc space to provided parallel endplates. Discspace spreader 70 can remain in the disc space during subsequentprocedures. It is further contemplated that lamina spreader 500, pediclescrew fixation with rods or plates on the other side of spinous processS may be used to maintain the distracted disc space height so that discspace spreader 70 can be removed. Distraction shims may also be used tomaintain disc space distraction, such as disclosed in co-pendingapplication entitled METHODS AND INSTRUMENTATION FOR DISTRACTION OF ADISC SPACE, filed Oct. 20, 1999, U.S. patent application Ser. No.09/421,709, which application is incorporated herein by reference in itentirety. In another form, lamina spreader 500 is not used by thesurgeon, and the surgeon only uses disc space spreader 70 to restore thenormal disc space height.

In FIG. 4( a) there is shown an alternate form for the distal portionsof disc space spreader 70 which facilitates spreader insertion throughopening 35. The proximal portion of the spreading instrument is similarto spreader 70 discussed above and will not be repeated here. Further,specific references are made to one alternate distal portion in thisdescription, it being understood that the second distal portion isidentical thereto. In addition, a spreader utilizing these alternatedistal portions can be used in the same manner as discussed above withrespect to disc space spreader 70. Central axis 88 between branches 72,74 is provided in FIG. 4( a) to orient distal portions 785, 786 withrespect thereto. Distal portions 785, 786 each have a distal working endthat includes spreading portion 778 that contacts the endplate of theadjacent vertebrae to apply a distraction force thereto. Distal portions785, 786 further include branch extension 777 extending from arespective one of the branches 72, 74 along axis 88.

A first lateral inset 779 extends from proximal portion 777 and has acentral axis 780 forming an angle A4 with respect to axis 88 such thatfirst lateral inset 779 extends in a first direction away from axis 88.A lateral offset 781 extends from first lateral inset 779 and has acentral axis 781 forming an angle A6 with central axis 88 and an angleA5 with central axis 780 such that lateral offset 781 extends in asecond direction with respect to axis 88 opposite the first direction,positioning the distal end of lateral offset 781 on the side of axis 88opposite first lateral inset 779. A second lateral inset 783 extendsfrom lateral offset 781 and has a central axis 784 forming an angle A5with central axis 782 and an angle A4 with central axis 88 such thatsecond lateral inset 783 extends in the first direction towards axis 88.Thus, first lateral insert 779 and second lateral inset 783 are parallelto one another. Spreading portion 778 extends from second lateral inset783 in the second direction away from axis 88 and has a central axis 787forming an angle A5 with central axis 88. Central axis 787 is notparallel to central axis 782 of lateral offset 781.

In one specific embodiment, it is contemplated that angle A4 is about 10degrees, angle A5 is about 125 degrees and angle A6 is about 45 degrees.In this specific embodiment, the length d1 along central axis 88 offirst lateral inset 779 is about 21 millimeters, the length d2 oflateral offset 781 along axis 88 is about 11 millimeters, and the lengthd3 of second lateral inset 783 along axis 88 is about 15 millimeters.

Referring now to FIG. 7, another alternate embodiment disc spacespreader/distracting mechanism is shown. Distractor 10 includes anelongated shaft 12 having a longitudinal axis 34. On the proximal end,distractor 10 includes a tool coupling 14 having a pair of opposeddriving surfaces 16 and 18. On the opposite distal end, distractor 10includes a distraction head 20 with a straight section 31 joined toshaft 12 by bend 32. Straight section 31 has a longitudinal axis 29disposed at an angle A1 with respect to longitudinal axis 34. In apreferred embodiment angle A1 is between 120 and 160 degrees.Distraction head 20 is joined to straight section 31 and has alongitudinal axis 33 at an angle A11 with respect to axis 29. In oneembodiment, angle A11 is between 20 and 60 degrees. Distraction head 20includes a pair of opposed distraction flats 26 and 28 separated by afirst height. A second pair of opposed flats 22 and 24 is separated by asecond height, the second height being greater than the first height.

In an alternative embodiment to distractor 10 shown in FIG. 8,distractor 50 may include a lever arm 62 to assist in rotation of thedistractor head after insertion into the disc space. Distractor 50includes a shaft 52 having a handle 54 opposite distractor head 56. Aswith the previous embodiment, distractor head 56 is joined to shaft 50 alateral offset that includes a bend 58 and a straight section 59.Additionally, shaft 53 includes multiple holes 60, which preferablyinclude an internal thread. Lever arm 62 has a connection end 66 adaptedto be removably received in a selected one of the holes 60. Handle 64tends to allow the surgeon to generate a substantial torque on head 56to rotate head 56 in the disc space.

Referring to FIG. 9, distractor 10 may be utilized to distract adjacentvertebrae. Distractor head 20 may be inserted into disc space D1 throughopening 35. Distractor head 20 may be inserted into the disc space D1until the distal tip is positioned adjacent the distal portion 37 andstraight section 31 is disposed in disc space D1 adjacent proximalportion 41. Distractor 10 is oriented during insertion in a reducedheight configuration such that surface 26 of head 20 engages theendplate of vertebra V1. In a similar manner, surface 28 engages upperadjacent vertebra V2. Thus, distractor head 20 creates a distractionheight approximating the distance between surfaces 26 and 28. Distractorshaft 12 is then moved to cause rotation about axis 33 of thedistraction head 20 bringing surfaces 22 and 24 into contact with theopposing endplate surfaces, thereby distracting the disc space to thesecond, greater height between surfaces 22, 24. Lamina spreader 500,pedicle screw fixation with rods or plates may be used to maintain discspace height. Distraction shims may also be used to maintain disc spacedistraction.

According to a further aspect of the invention, various reamers areprovided with the present invention to remove soft tissues from the discspace and the cartilage layer from the adjacent vertebral endplates. Astraight reamer is illustrated in FIG. 10 and a curved reamer isillustrated in FIG. 11. Straight reamer 200 includes a hollow outershaft 202 with a handle 204 attached to the proximal portion thereof. Arotatable inner shaft 206 is disposed within outer shaft 202. Rotarycutting head 210 having a cavity 213 is coupled to inner shaft 206. AHudson type tool coupler 208 is provided at the proximal portion ofinner shaft 206. It will be understood that a manual handle, such as aT-handle, may be attached to tool coupler 208. Application of rotationforce on the inner shaft turns cutting head 210. Straight reamer 200 isinserted through opening 35 to remove material from proximal portion 41of disc space D1, as shown in FIG. 13. Cutting head 210 of curved reamer200 may be moved to various locations in the proximal portion 41 of discspace D1 and the cutting head reinserted to widen or alter a previouslyformed channel. A powered rotary driver may also be coupled to toolcoupler 208 to mechanically drive inner shaft 206 and rotate cuttinghead 210.

Referring now to FIG. 11, curved reamer 220 includes a hollow outershaft 222 with a handle 224 attached to the proximal portion thereof. Arotatable inner shaft 226 is disposed within outer shaft 222. Rotarycutting head 210 (identical to the head provided on reamer 200) having acavity 213 is coupled to inner shaft 206. Outer shaft 222 includes abend 221 angled at offset angle A3, permitting insertion of cutting head210 through opening 35 and into distal portion 37 of disc space D1, asshown in FIG. 14. It is contemplated that A3 may range from 100 to 150degrees. In one specific embodiment, angle A3 is about 125 degrees.Further, while a fixed bend is shown for the purpose of illustration inFIG. 11, it is contemplated that outer shaft 222 may include a flexibleportion or mechanical coupling permitting a plurality of angles for bend221. Inner shaft 226 is preferably flexible at least through bend 221 sothat rotary torque can be transmitted through bend 221. The flexibleinner shafts used with the instruments of the present invention can bemade from, for example, stainless steel coiled wire or nitinol.

A Hudson type tool coupler 228 is provided at the proximal portion ofinner shaft 226. It will be understood that a manual handle, such as aT-handle, may be attached to tool coupler 228 to permit application ofrotation force on the inner shaft and turn cutting head 210.Alternatively, a powered rotary driver may be coupled to tool coupler228 to mechanically drive inner shaft 226 and rotate cutting head 210.As shown in FIG. 14, cutting head 210 of curved reamer 220 may be movedto various locations in the distal portion 37 of disc space D1 and thecutting head reinserted to widen or alter a previously formed channel.Thus, straight reamer 200 and curved reamer 220 allow the surgeon toremove disc material, cartilage and other tissue in both proximalportion 41 and distal portion 37 of disc space D1 through opening 35.

As shown in FIG. 12, cutting head 210 includes cutting edges 211 a, 211b, 211 c, and 211 d. Cutting head 210 has a smooth, non-cutting profilebetween edges 211 a, 211 d and between edges 211 b, 211 c. It iscontemplated that head 210 is inserted with the non-cutting profilesoriented towards the vertebral endplates to provide smooth insertion andpositioning of cutting head 210 in the disc space. The location ofcutting head 210 in the disc space may be checked by any knownvisualization techniques before proceeding to tissue removal. Whencutting head 210 is rotated in direction R1, edges 211 a and 211 c cuttissue and cartilage, while edges 211 b and 211 d pass over the tissuewithout cutting. The cut material is deposited in cavity 213, where itmay then be extracted from the disc space. Cutting head 210 provides asafe and efficient discectomy tool that preserves the bony endplatesurface and quickly collects the soft tissue.

Other embodiments of cutting instruments are provided that include aguide member for controlled cutting within the proximal and distalportions of the disc space. Referring to FIGS. 15 and 16, a guidedrotary cutter is disclosed. Cutter 100 includes a guiding shaft 102having an interconnected handle 109 disposed on the proximal end and astop 106 disposed on the opposing distal end. Stop 106 may besubstantially radiopaque to provide an indication of inner shaftlocation on x-ray images. Distal portion 103 is joined to shaft 102 bybend 104. Bend 104 is preferably a substantially uniform curve creatingangle A3 between axis 105 of shaft 102 and axis 107 of distal portion103.

Disposed on guide shaft 102 between handle 109 and stop 106 is an outershaft 108. Outer shaft 108 includes a handle 110 on a proximal end and aflexible drive 112 on the opposing distal end. A cutting head 114 isinterconnected with flexible drive 112. As shown more clearly in FIG.16, cutting head includes a number of cutting blades configured forrotary cutting. Flexible drive 112 is designed to transmit bothlongitudinal force to advance cutting head along guiding shaft 102 inthe direction arrow 116 and also transmit rotation force in thedirection of arrow 118 to move cutting head 114 in a circular mannerabout shaft 102, thereby engaging cutting blades 120 with adjacenttissues. While other flexible drives, such as, for example but withoutlimitation, cables and mechanical couplings may be utilized, in apreferred embodiment flexible drive 112 is a helically wound cable.

Referring to FIG. 17, cutter 100 may be inserted into disc space D1through opening 35. Preferably, stop 106 is positioned adjacent distaldisc space portion 37 and bend 104 may be positioned centrally in thedisc space. The location of guide shaft 102 in the disc space may bechecked by any known visualization techniques before proceeding totissue removal. Once the proper positioning of the guide shaft 102 hasbeen established, force is applied to handle 110 to advance cutting head114 into contact with structures adjacent the disc space. Forwardpressure in the direction of arrow 116 may be maintained as rotationalforce in the direction of arrow 118 is transmitted to cutting head 114.As tissue is removed cutting head 114 may cuttingly advance along guideshaft 102 until it reaches stop 106. Cutting head 114 has an internalchannel (not shown) sized to receive shaft 102 but limited in size andshape such that the cutting head may not extend beyond stop 106. As willbe understood by the illustrations, cutting tool 100 forms an arcuatechannel through the disc space by following guiding shaft 102. Guideshaft 102 may be moved to one or more new locations in the disc spaceand the cutting head reinserted to widen or alter a previously formedchannel in disc space D1.

A further embodiment of a rotary cutting device is disclosed in FIGS. 18through 20. Shaver 150 includes a guide rod 152 with a handle 158disposed at the proximal end and a stop 156 disposed on the distal end.Guide rod 152 includes bend 154 adjacent the distal end. Outer shaft 160is slidably mounted on guide rod 152. Outer shaft 160 includes a handle162 on its proximal end and is coupled to flexible drive 164 on itsdistal end. A shaving head 166 is mounted on flexible drive 164.Preferably, shaving head 166 has a plurality of cutting blades adaptedto shave tissue as the head is rotated. In one aspect, individual bladesof head 166 are elongated and include a forward cutting blade 168 andbackward cutting blade 170 and a cavity 169 for deposit of material.Still more preferably, shaving head 166 has sufficiently flexibility toallow it to conform at least partially to bend 154 as it is advancedalong guide rod 152 towards stop 156.

In use, shaver 150 may be positioned in disc space D1 with stop 156disposed adjacent distal disc space portion 37 as shown in FIG. 20.Preferably, shaver 150 will follow use of cutter 100 to further defineand expand the arcuate channel defined in the disc space. As shaver head166 is advanced in the direction of arrow 174, handle 162 may be rotatedthereby rotating head 166 in the direction of arrow 173 to cut tissue,and cut tissue can be accumulated between the blades and in cavities 169for removal from disc space D1. Shaver head 166 preferably cuts in bothdirections, however it is also contemplated that the shaver may beunidirectional.

Referring now to FIGS. 21 and 22, an alternative shaver head 180 isillustrated. Shaver head 180 is slidably disposed on inner shaft 182 andmay be advanced along the shaft until it reaches stop 186. Shaver head180 includes a flexible drive portion 190 and a helical cutting blade188 disposed on the distal portion of the flexible drive. Thus, asflexible drive 190 rotates, helical blade 188 cuts the tissue andaccumulates tissue between the blades for removal from the disc space.

Referring to FIGS. 23–26, further cutting instruments according to thepresent invention are shown. In FIG. 23 there is illustrated a pushscraper 260. Push scraper 260 includes an elongated shaft 262 with ahandle 264 on the proximal end and a push scraper head 265 on the distalend. Scraper head 265 is joined to and is substantially perpendicular toshaft 262. As shown in FIG. 23( a), scraper head 265 includes distallyfacing upper and lower cutting blades 266 having a distal concave face267 with a hole 268 formed therein. Concave face 267 forms a trougharound hole 268. The proximal face 269 of scraper head 265 has a smooth,convex non-cutting profile to facilitate proximal movement of scraperhead 265 through the disc space. As shown in FIG. 25, push scraper 260is inserted through opening 35 with scraper head 265 initiallypositioned towards proximal portion 41 of disc space D1. Push scraper260 is then pivoted and pushed distally through disc space D1, asindicated by push scraper 260′, to position scraper head 265′ towardsdistal portion 37 of disc space D1. Distally facing blades 266 removedisc material and can deposit at least some of the material in thetrough between blades 266 during this distal pivotal movement forsubsequent removal. A pusher as described herein can be used tofacilitate this distal pivotal movement.

In FIG. 24 there is illustrated a pull scraper 270 includes an elongatedshaft 272 with a handle 274 on the proximal end and a pull scraper head275 on the distal end. Scraper head 275 is joined to and extendssubstantially perpendicular to shaft 272. Scraper head 275 includesproximally facing cutting blades 276 and a concave proximal face 277with a hole 278 formed therein. Concave face 277 forms a trough aroundhole 278. The distal face 279 of scraper head 275 has a smooth, convexnon-cutting profile to facilitate distal movement of scraper head 275through the disc space. As shown in FIG. 26, pull scraper 270 isinserted through opening 35 and scraper head 275 is pushed through discspace D1 to initially position scraper head 275 towards distal portion37 of disc space D1. Pull scraper 270 is then pivoted and pulledproximally through disc space D1, as indicated by pull scraper 270′, toposition scraper head 275′ towards proximal portion 41 of disc space D1.Proximally facing blades 276 remove any remaining disc material and candeposit at least some of the material in the trough between blades 276during this proximal pivotal movement for subsequent extraction.

When the desired amount material has been removed from disc space D1using the instruments described above, a straight chisel 540 as shown inFIG. 27 is provided for preparing a square entrance port into disc spaceD1 for implant insertion. Chisel 540 includes shaft 542 having a handle544 coupled to the proximal end of shaft 542. A chisel head 546 isprovided at the distal end of shaft 542. Chisel head 546 includes a bodyportion 547 having a pair of non-cutting extensions 548 extendingdistally therefrom. Extensions 548 have an upper surface 548 a forcontacting vertebra V2 and a lower surface 548 b for contacting lowervertebra V1. Extensions 548 guide chisel head 546 into the disc space,ensuring equal amounts of material are removed from the endplates of theupper and lower vertebrae by upper cutting edge 550 and lower cuttingedge 551. V-shaped portions 552, 553 distally offset edges 550, 551,respectively, with respect to body portion 547. A chamber 554 is formedin body portion 547, and body portion 547 has upper and lower openingspositioned proximally of the upper and lower cutting edges 550, 551. Cutmaterial can be deposited through these upper and lower openings andinto chamber 554.

Referring now to FIG. 28, chisel 540 is shown with extensions 548 indisc space D1. Chisel head 546 is impacted into the disc space, withcutting edges 550, 551 removing bone material and osteophytes from thevertebral endplates. This provides, as shown in FIG. 29, an enlargedsquared entrance to disc space D1 is formed at the proximal portion ofthe disc space that is larger than the opening created by spreading thelamina and distracting disc space D1. This enlarged entrance facilitatesimplant insertion into the disc space. The material removed to form theenlarged entrance is indicated by cut-away portions C in vertebra V1 andV2.

Referring now to FIGS. 30 through 32, there is shown a guided chiselwhich can be used, if desired, to remove material from distal portion 37of disc space D1. Chisel 230 includes an inner shaft 232 with a handle238 connected to the proximal end and a stop 236 formed on the distalend. As shown in FIG. 31, inner shaft 232 preferably has a non-circularcross section 233 adjacent the distal portion. The non-circular crosssection, preferably square, inhibits rotation of the chisel cutting headas it is impacted along inner shaft 232. Outer shaft 240 is slidablydisposed about inner shaft 232. Outer shaft 240 includes a drive region242 with an impact shoulder 244. Outer shaft 232 is coupled to chiselhead 248 by flexible drive 246. Chisel head 248 includes an uppercutting edge 254 and a lower cutting edge 252. The cutting blades arespaced by extensions 249 and 251 that control and limit the depth ofpenetration of the cutting edged into the endplates.

As shown in FIG. 32, inner shaft 234 is positioned in disc space D1through opening 35. Stop 236 is position adjacent the distal portion 37of disc space D1. Visualization of the placement of inner shaft 234 maybe made to confirm proper positioning. Once the position in confirmed,chisel head 248 is advanced along inner shaft 232 in the direction ofarrow 250. If necessary, a forked slap hammer or pusher may bepositioned with the forks extending on either side of drive region 242.The slap hammer may then be forcibly urged against impact shoulder 244to drive chisel head 248 into the disc space. The chisel head isadvanced until it engages stop 236. This action forms a substantiallysquare or rectangular arcuate channel extending into each of theadjacent vertebral endplates.

Referring now to FIGS. 33 through 34 there is provided an implanttemplate inserter 560 according to another aspect of the presentinvention. Template inserter 560 includes a shaft 562 having a handle564 detachably secured to the proximal end of shaft 562. A bend 566 issecured to the distal end of shaft 562 and forms offset angle A3. Atemplate 568 is secured at the distal end of bend 566. A notch 567 isprovided in shaft 562 that is engageable by a pusher, such as pusher 670described below, to facilitate placement of template 568 into disc spaceD1. Template 568 is positionable through opening 35 into the distalportion of disc space D1 to determine if enough material has beenremoved from the disc space to accommodate the implant to be insertedtherein, or to determine the size of implant required. Handle 564 isremovable for fluoroscopic or radiographic imaging of template 568 indisc space D1, allowing the surgeon to confirm the fit and positioningof template 568 in disc space D1. Templates 568 of various heights hihaving various sized bends 566 can be provided so the surgeon canperform multiple trials to obtain information as to the proper implantsize.

Referring now to FIGS. 35 and 35( a), there is shown an implantinsertion guide 600 according to another aspect of the presentinvention. Insertion guide 600 has a proximal portion that includes afirst branch 602 pivotally joined to a second branch 604 by pin 606.Extending distally from pin 606 are distal portions 615 and 616 ofbranches 602 and 604, respectively. Distal portions 615 and 616 have adistal working end that includes guide members 608 and 610 extendingfrom lateral offsets 609 and 611, respectively. Offset portions 609 and611 have a straight portion extending generally parallel to and offsetby distance d from axis 618, and a bend forming a first offset angle A2with axis 618. Guide members 608 and 610 have an arcuate form extendingfrom offset portions 609, 611 to the distal tip insertion guide 600.This shape generally corresponds to the shape of the implant insertionpath P, as discussed below. Guide members 608, 610 preferably have alength and shape such that the distal tip of inserter guide 600 ispositionable in the desired location in distal portion 37 of disc spaceD1. These offset portions 609, 611 laterally offset branches 602, 604from guide members 608, 610. This provides room for placement of animplant insertion instrument, such as those described below, or theimplant template inserter 560 described above, alongside branches 602,604. The implant can be slid along guide members 608, 610 and into thedisc space, and guide members 608, 610 provide a barrier that protectsthe anterior portion of the disc space during implant insertion.

In a preferred embodiment branches 602 and 604 of inserter guide 600 canbe manipulated to separate guide portions 608, 610 and place guideportions 608, 610 in contact with the vertebral endplates. This contactallows the desired position of guide members 608, 610 to be maintainedduring implant insertion. Further, such separation capabilities might berequired in order to further distract disc space D1 to facilitateimplant insertion or removal. Inserter guide 600 includes a mechanism toforce and/or maintain the separation of guide members 608 and 610. Thespreading mechanism includes an externally threaded rod 612 joined tobranch 602 and extending through hole 613 formed in the proximal end ofbranch 604. The spreading mechanism has an internally threaded hand nut614 threadedly received on rod 612. Branches 602 and 604 may be forcedtogether by action of internally threaded nut 614 on branch 604 forcingit towards branch 602, thereby forcing guide members 608 and 610 apartand into contact with the vertebral endplates.

Referring now to FIG. 36, there is shown a straight implant inserter630. Inserter 630 includes a rigid hollow outer shaft 632 secured to ahandle 634 at the proximal end of shaft 632. An inner shaft 636, eitherrigid or flexible, extends through outer shaft 632 and includes animplant connector 638 at its distal end extending distally from thedistal end of outer shaft 632. Implant connector 638 is preferablythreaded, but can include other attachment means for engaging theimplant. Inner shaft hand nut 642 is coupled to inner shaft 636, and canbe rotated to in turn rotate connector 638 to secure or release theimplant thereto as desired. A bearing member 640 is secured to outershaft 636, and contacts the wall of implant to direct an insertion forceto the implant.

Referring now to FIGS. 37–38, there is shown a curved inserter 650 and apusher 670 adapted for use with the curved inserter 650 and otherinstruments of the present invention. Inserter 650 includes a rigidhollow outer shaft 652 secured to a handle 654 at the proximal end ofshaft 652. Outer shaft 652 includes a bend 655 adjacent its distal endforming offset angle A3. A flexible inner shaft 656 extends throughouter shaft 652 and bend 655. Inner shaft 656 includes an implantconnector 658 at its distal end extending distally from the distal endof outer shaft 652. Implant connector 658 includes threads or otherattachment means for engaging an implant. Inner shaft hand nut 662 iscoupled to inner shaft 656, and can be rotated to in turn rotateconnector 658 to secure or release the implant thereto as desired. Abearing member 660 is secured to outer shaft 656, and contacts the wallof the implant to direct the insertion force thereto. An impaction toolengaging portion 664 in the form of a notch formed around outer shaft664 is provided in outer shaft 652.

An impaction tool or pusher 670 includes a shaft 672 having a bulbhandle 674 secured to the proximal end of shaft 672. A shaft engagingportion 674 is secured to and extends from the distal end of shaft 672.In the illustrated embodiment, shaft engaging portion 674 is a U-shapedprong, and is positionable in notch 664 to apply a pushing force tocurved inserter 650 to facilitate placement the implant secured toinserter 650 into distal portion 37 of disc space D1.

Insertion of implant I with curved inserter 650 is shown in FIG. 39.Implant I is attached to inserter 650, and implant I is then positionedin opening 35 with inserter 650 oriented such that it extends acrossspinous process S. As implant I is advanced from proximal portion 41 todistal portion 37 of disc space D1, inserter 650 is pivoted aroundspinous process S to the position indicated by inserter 650′. Pusher 670can be used to facilitate insertion by allowing the surgeon to usepusher 670 to apply the insertion force with one hand while the otherhand is used to pivot inserter 650.

An alternate embodiment implant insertion device is shown in FIGS. 40through 44. The implant inserter 300 includes an inner guiding shaft 302having a handle 308 attached to one end and a stop 306 disposed on theopposite end. Guiding shaft 302 includes a bend 304 adjacent the distalportion. Insertion sleeve 310 is slidably disposed about inner shaft302. As previously described with respect to chisel 230, insertionsleeve 310 includes a drive portion 314 and impact shoulder 316 for usewith a slap hammer, if necessary. Insertion sleeve 310 is connected atits distal end to an implant driver 318 by a flexible drive member 312.Implant driver 318 includes an arcuate cavity 322 having a substantiallyconcave surface. The concave surface terminates adjacent the inner shaft302.

As shown in FIGS. 42 through 43, an implant 330 is engaged to implantdriver 318 with a portion of the implant positioned in arcuate cavity322. Driver 318 urges implant 330 in the direction of arrow 320. It willbe understood that driver 318 and guide rod 302 cooperate to guide theimplant along an arcuate path through the disc space formed by guide rod302. Implant 300 is one example of an implant that may be inserted withinstruments according to the present invention. Further suitableimplants are disclosed in U.S. Pat. No. 5,897,556 and also in PCTInternational Application PCT/US00/41392 entitled IMPACTED ORTHOPEDICBONE SUPPORT IMPLANT, each of which is incorporated herein by referencein its entirety. The implant inserted with the instruments andtechniques of the present invention could also be a spacer, a discprosthesis or disc nucleus prosthesis.

As shown in FIG. 44, inner shaft 302 of implant inserter is positionedin disc space D1 with stop 306 positioned adjacent distal portion 37.Implant 330 is positioned in opening 35 and implant driver 318 is urgedforwardly along guide shaft 304 to drive the implant to distal portion37 of disc space D1 as shown in FIG. 45. Once implant 330 is positionedin the desired location, bone ingrowth promoting material may bepositioned around implant 330 using guide rod 302 as a guide forplacement. Bone ingrowth promoting material 331 can also be placed inthe interior portions of implant 330 prior to placement. Additionally,bone ingrowth promoting material 342 may be positioned in the anteriorportion 39 of the disc space. As shown in FIG. 46, a second implant 349may be placed in the proximal portion 41 of the disc space to complete abilateral placement of implants to provide balanced structural supportin disc space D1. Second implant 349 may also be filled with bone growthpromoting material 351.

While some of the above-described instruments illustrate a separateguide rod for each instrument, it is contemplated that a single guiderod may be positioned in the disc space and multiple instrumentsadvanced over the guide rod to complete disc space preparation andimplant insertion. Further, the stop on the guide rod may includeselectively engageable portions that may be engaged with the vertebralendplates to maintain the position of the guide rod in the disc space.

In a further alternative embodiment implant shown in FIG. 47, the discspace is prepared using the any combination of instruments describedabove. The anterior portion 39 of the disc space may be packed with boneingrowth promoting material 342. A dual lobe implant 370, which can havefeatures such as those described below with respect to implant 1000, isplaced in the disc space D1 and has a length sufficient to span the discspace from the distal portion 37 to the proximal portion 41. Implant 370includes a first distal lobe 372 and a second proximal lobe 374. Acentral opening 376 is provided that may be filled with bone ingrowthmaterial. Implant 370 may be positioned by using any of the implantinserters described herein.

FIG. 48 illustrates one example another embodiment implant inserteraccording to the present invention. Implant inserter 400 includes anelongated shaft 402 with a handle 404 at its proximal end and animplant-gripping end at the opposite end. The implant-gripping endincludes bifurcated branches 408 and 410 separated by a space 412. Thebifurcated branches each include a bend 406 to accommodate implantplacement through opening 35 and into disc space D1. Branch 408 includesan inclined surface 414 and an implant engagement block 418. Similarly,branch 410 includes inclined surface 416 and an implant engagement block420. Each engagement block includes at least one projection (not shown)for insertion into a wall opening of implant 422 having a bearingsurface to engage implant 422. An outer sleeve 424 is slidably disposedon inner shaft 402 with an internal channel 426. It will be understoodthat as sleeve 424 is advanced toward implant 422, sleeve 424 willengage inclines 414 and 416 thereby urging branches 408 and 410 towardseach other. The projections on engagement blocks 418 and 420 will thenfirmly engage implant 422.

In a further embodiment illustrated in FIG. 49, implant inserter 450 hasan implant engagement end 456 offset from shaft 452 by a bend 454. Apusher 460 includes a handle 464 at one end and a projection (not shown)at the opposite end 462 for engagement with a corresponding opening (notshown) on shaft 452. Pusher 460 provides a mechanism for the surgeon touse one hand to urge implant 458 across disc space D1, while the otherhand of the surgeon pivots implant 458 with inserter 450 as it is movedacross disc space D1. The longitudinal axis of pusher 460 is inrelatively substantial alignment with the longitudinal axis of implantengagement end 456. Thus, longitudinal force applied on pusher 460 maybe directly transmitted as longitudinal force to advance implant 458into the disc space.

Referring to FIGS. 50–51, an intradiscal rasp 700 according to thepresent invention is shown that is useful for disc space preparationwith the approaches discussed herein. It is further contemplated thatrasp 700 also has application with approaches and intradiscal proceduresother than those discussed herein. Rasp 700 includes an elongated shaft702 with a handle 704 on the proximal end of shaft 702 and a raspinghead 705 on the distal end of shaft 702. Shaft 702 has a distal portion708 laterally offset from a proximal portion 706 to facilitate insertionof rasping head 705 into the disc space. Rasping head 705 is joined toand extends laterally from distal portion 708 and has a leading end wall722 that is laterally offset from proximal portion 708 in the samedirection as but to a greater extent than distal portion 708. Theconfiguration of shaft 702 also allows the surgeon to place rasping head705 in contact with the vertebral endplates to prepare distal portion 37of disc space D1 for implant insertion. Shaft 702 and rasping head 705are configured in a manner that further allows preparation via aposterior lateral approach of at least a portion of the anterior thirdof the disc space for receipt of an implant. In order to match theendplate area prepared to the implant, rasping head 705 can have a sizeand shape, when viewed in the direction of the vertebral endplates, thatgenerally corresponds to the size and shape of the implant to beinserted. In the illustrated embodiment, rasping head 705 has agenerally banana or boomerang shape that generally corresponds to theshape of the vertebral endplate contacting surfaces of the implant 1000discussed below. However, it should be understood that rasping head 705can also be used for implants having other shapes, including circular,semi-circular, square, rectangular, or ovoid shapes, to name a few.

Further details regarding shaft 702 and rasping head 705 will now bediscussed. Shaft 702 has proximal portion 706, distal portion 708, andan intermediate connecting portion 710 extending between and joiningproximal portion 706 and distal portion 708. Proximal portion 706extends along a central axis 707, distal portion 708 extends along acentral axis 709, and connecting portion 710 extends along a centralaxis 711. Shaft 702 forms an angle A2 between central axis 707 andcentral axis 711, and an angle A22 between central axis 711 and centralaxis 709. Thus, connecting portion 710 laterally offsets distal portion708 from proximal portion 706 a distance d. In one specific embodiment,this distance d is about 10 millimeters. Rasping head 705 extends fromshaft 702 such that its leading end wall 722 is positioned even furtherlaterally offset from proximal portion 706 than distal portion 708. Thisconfiguration allows shaft 702 to be initially positioned across spinousprocess S (such as shown with respect to inserter 1000 in FIG. 53) andthen pivoted in the direction of arrow R away from spinous process S asrasping head 705 is inserted into disc space D1. Rasping head 705 canthus be used by the surgeon to create a rasped endplate portion on eachvertebral endplate that generally corresponds to the implant insertionpath.

As shown in FIG. 51, rasping head 705 includes a first rasping surface712 and an opposite second rasping surface 714. Rasping head 705 furtherincludes an anterior wall 718, a posterior wall 720, leading end wall722 and a trailing end wall 724. Rasping head 705 is connected, mounted,integrally formed with, or otherwise attached to shaft 702 at trailingend wall 724. Each of these walls 718, 720, 722, and 724 has a smoothsurface finish, and leading end wall 722 is rounded to provide a smoothtransition between anterior wall 718 and posterior wall 720. Anteriorwall 718 has a convex profile that, in addition to generally matchingthe shape of the anterior wall of implant 1000, also generallycorresponds to the shape of the anterior inner annulus wall and cancontact this annulus wall to limit insertion depth of rasping head 705.Posterior wall 720 has a slightly concave profile of less curvature thananterior wall 718, and posterior wall is shorter than anterior wall 718between leading end 722 and trailing end 724. Posterior wall 724generally corresponds to the shape of the posterior edge of thevertebral endplate.

In an alternate embodiment shown in FIGS. 50( a) and 51(a), rasp 700 hasa rasping head 705′ with a leading end wall 722′ that is bulleted ortapered to facilitate entry of rasping head 705′ into the disc space.This alternate embodiment further includes a rasping surface on theanterior wall 718′ that can scrape material in the anterior portion ofthe disc space. First and second rasping surfaces 712′, 714′ can be usedto rasp material from the vertebral endplates. In this embodiment,posterior wall 702′, leading end wall 722′ and trailing end wall 724′have a smooth surface finish.

Rasping surfaces of rasp 700 are provided with a surface configurationthat allows that surgeon to scrape endplate material as the rasp ismoved across the endplate. In one form, this rasping surfaces includes aplurality of pyramid-shaped teeth each having their upper most pointpositioned to contact the vertebral endplate. It is further contemplatedthat other rasping surfaces known to those skilled in the art could beprovided, such as, for example, a plurality of frusto-conicalprojections, spikes, diamond-shaped projections, or wedge-shapedprojections that each extend across the width of the rasping surface.Rasping surfaces 712, 714 can simultaneously contact the adjacent upperor lower vertebral endplates, or rasp 700 can be manipulated in the discspace to selectively contact one of the upper endplate or the lowerendplate. In one specific embodiment, rasping head 705 has a height 716between the outermost ends of the rasping surfaces 712, 714 of 8millimeters. In another specific embodiment, height 716 is 6millimeters. However, it should be understood that other heights arealso contemplated so long as rasping head 705 can be positioned in theintradiscal space.

Referring now to FIGS. 52–53, another embodiment implant and instrumentset for inserting the implant into disc space D1 through opening 35 areprovided. The instrument set includes an implant insertion tool in theform of inserter 1100, an impaction tool in the form of pusher 1200, anddriver 1300. Inserter 1100 has a proximal portion with a shaft 1106 anda handle 1108 secured to the proximal end of shaft 1106. Shaft 1106includes has a distal working end having a rotatable connecting portion1102 with a threaded distal end portion 1104 for engaging a threadedopening on implant 1000. A male protrusion member 1105 extends from endportion 1104, and is positionable in a slot formed in implant 1000 asdescribed further below. Driver 1300 is engageable to the proximal endof connecting portion 1102 to thereby rotate connecting portion 1102 tothreadingly engage implant 1000 to threaded end portion 1104 of inserter1100. Shaft 1106 further includes a lateral offset 1110 having a bendforming angle A2 with shaft 1106 and an angle A22 with distal shaftportion 1111, and is configured similar to the shaft of rasp 700discussed above. Distal portion 1111 is thus offset from the proximalportion of shaft 1106 by distance d. In one specific embodiment, thisoffset distance is about 10 millimeters. This allows shaft 1106 to beinitially positioned across spinous process S, as shown in FIG. 53, andthen pivoted in the direction of arrow R away from spinous process S asimplant 1000 is positioned in disc space D1. Pusher 1200 has a shaft1202 and handle 1204 at the proximal end of shaft 1202. Pusher 1200further includes a reduced diameter distal end portion 1206 positionablein an impaction tool engaging portion in the form of bore 1112 formed inshaft 1106.

The surgeon can use pusher 1200 to apply a pushing force to implant 1000in the direction of arrow P while inserter 1100 is pivoted in thedirection of arrow R to pivot the leading end of implant 1000 towardsdistal portion 37 of disc space D1. It should be understood thatinserter 1100 does not pivot with respect to implant 1000, but ratherinserter 1100 follows the proximal end of implant 1000 as the distal endof implant 1000 is pivoted to move implant 1000 non-linearly into andacross the disc space along insertion path P. The inserter 1100 andpusher 1200 provide the surgeon the ability to use two-handed control toinsert implant 1000 into the disc space along non-linear path P sincethe surgeon controls inserter 1100 with one hand while the other handprovides a pushing or impaction force on implant 1000 with pusher 1200.

Referring now to FIGS. 54–58, various views of implant 1000 are shownand will now be described in further detail. Implant 1000 is aninterbody fusion device or cage that can be packed with bone growthmaterial or other known substance and inserted into disc space D1 topromote bony fusion between vertebrae V1 and V2. Furthermore, thestructural features of implant 1000 can have application for a discprosthesis or a disc nucleus prosthesis that is to be inserted into discspace D1 through opening 35. Implant 1000 has a boomerang or bananashape that is suited for insertion to provide bilateral support in discspace D1 through a unilateral approach, after the disc space D1 has beenaccessed and prepared using the above described instruments andtechniques. It is also contemplated that disc space D1 can be accessedand prepared for implant insertion using any other known techniques andinstruments and other approaches to the disc space, such as lateral,anterior or antero-lateral approaches, for inserting implant 1000.However, a particular problem exists providing bilateral support to theintradiscal space in instances where the disc space is accessed from aposterior lateral approach, such as a transforaminal approach, due tothe difficulty in accessing and inserting the implant into distalportion 37 of disc space D1. Implant 1000 addresses this problem byproviding a design that is suited for insertion into opening 35 and forsubsequent pivotal movement and impaction movement through disc space D1into distal portion 37.

Implant 1000 includes a concave posterior wall 1002 and an oppositeconvex anterior wall 1004. Implant 1000 further includes an arcuateleading end wall 1006 and an arcuate trailing end wall 1008. Each of theend walls 1006, 1008 extend between and connect posterior wall 1002 andanterior wall 1004, and provide a smooth transition therebetween tofacilitate passage of implant 1000 through disc space D1. Implant 1000further includes an upper bearing member 1010 and a lower bearing member1012 extending between and connecting walls 1002, 1004, 1006 and 1008.

Implant 1000 has a height H1 at the medial portion of posterior wall1002 and a second height H2 at the medial portion of anterior wall 1004.Upper bearing member 1010 and lower bearing member 1012 have a slightconvexity between the anterior and posterior walls 1002, 1004 and heightH2 is preferably greater then H1 in order to correspond to the anatomyof the vertebral endplates at the posterior portion of disc space D1.Leading end wall 1006 and trailing end wall 108 further have a height H3that is less than H1 and H2, and upper bearing member 1010 and lowerbearing member 1012 have a slight convexity between leading end 1006 andtrailing end 1008 as best shown in FIG. 56. This double convexitypreferably matches the double concavity of the adjacent vertebralendplate. Furthermore, the difference in heights between the upper andlower bearing members at the anterior and posterior walls can beprovided so as to establish lordosis when implant 1000 is inserted inthe disc space. Implant 1000 thus has application in restoring andmaintaining spinal lordosis from a postero-lateral approach.

Upper bearing member 1010 can further be provided with a number ofgrooves 1014 and lower bearing member 1012 can be provided with a numberof grooves 1016. Grooves 1014 and 1016 can engage the vertebralendplates to resist posterior and anterior migration of implant 1000 inthe disc space.

In order to promote fusion, the walls and bearing members of implant1000 are provided with a number of openings. Upper bearing member 1010includes upper openings 1018 a and 1018 b separated by an upper strut1019. Lower bearing member 1012 includes lower openings 1020 a and 1020b separated by a lower strut 1021. An upper bar 1022 forming theperimeter of upper bearing member 1010 has a boomerang shape, andsurrounds upper openings 1018 a, 1018 b and is connected to strut 1019.Similarly, a lower bar 1024 forming the perimeter of lower bearingmember 1012 has a boomerang shape, and surrounds lower openings 1020 a,1020 b and is connected to strut 1021. Posterior wall 1002 includes apair of posterior lateral openings 1026 a and 1026 b adjacent to theposterior side of leading end wall 1006 and trailing end wall 1008,respectively. Posterior vertical struts 1030 a and 1030 b extend betweenand are connected to upper bar 1022 and lower bar 1024 on the medialside of openings 1026 a and 1026 b, respectively. A posterior middleopening 1028 that is larger than posterior lateral openings 1026 a, 1026b is defined between vertical struts 1030 a, 1030 b.

Anterior wall 1004 includes a pair of anterior lateral openings 1032 band 1032 a adjacent to the anterior side of leading end wall 1006 andtrailing end wall 1008, respectively. Anterior vertical struts 1034 aand 1034 b extend between and are connected to upper bar 1022 and lowerbar 1024 on the medial side of openings 1032 a and 1032 b, respectively.An anterior middle opening 1036 that is larger than anterior lateralopenings 1032 a, 1032 b is defined between vertical struts 1034 a, 1034b. An offset strut 1038 is provided at the middle of opening 1036, andextends between and is connected with upper bar 1022 and lower bar 1024.Since offset strut 1038 is offset toward posterior wall 1002, and offsetstrut 1038 is also connected with upper strut 1019 and lower strut 1021.As best shown in FIG. 54, offset strut 1038 and middle opening 1036provide upper member 1010 with an upper cantilevered portion 1040 andlower member 1012 with a lower cantilevered portion 1042. Thecantilevered portions 1040, 1042 facilitate x-ray assessment of fusionin the middle of disc space D1 since there is no structural memberblocking an x-ray image taken from a lateral view.

Implant 1000 is also provided with an inserter engaging portion 1048 attrailing end 1008 and an identical inserter engaging portion 1044 atleading end 1006 so that implant 1000 is insertable into disc space D1from a unilateral approach taken on either side of the spinous process.Inserter engaging portions 1044, 1048 are preferably internally threadedand engageable with a distal end of an implant inserter, such asthreaded end portion 1104 of inserter 1100 described above. A slot 1046extends upwardly and downwardly from inserter engaging portion 1044 toupper bearing member 1010 and lower bearing member 1012. A slot 1050extends upwardly and downwardly from inserter engaging portion 1048 toupper bearing member 1010 and lower bearing member 1012. Slots 1046,1050 receive male member 1105 of inserter 1100 to prevent rotation ofimplant 1000 with respect to inserter 1100 when implant 1000 is engagedthereto. The cooperation between slots 1046, 1050 and male member 1105also properly orients inserter 1100 with respect to implant 1000 whenimplant 1000 is engaged thereto.

Referring now specifically to FIG. 55, implant 1000 has an axis Cextending through its center longitudinally. Axis C extends generally inthe direction between the leading end and the trailing end of implant1000, and is equal distance from the most posterior point A on leadingend wall 1006 and the most posterior point B on trailing end wall 1008.Leading end wall 1006 is offset to the posterior side of axis C, andtrailing end wall 1008 and engaging portions 1044, 1048 are also offsetto the posterior side of axis C. The offset in the leading end andtrailing ends of implant 1000 facilitates the controlled insertion ofimplant 1000 along curved insertion path P.

One method for inserting implant 1000 will now be described withreference to FIGS. 52 and 53. Driver 1300 is used to connect implant1000 to connecting portion 1104 of inserter 1100. Distal end portion1206 of pusher 1200 is positioned in bore 1112 in shaft 1106. Theleading end 1106 of implant 1100 is placed at the opening 35. A manualor mechanical impaction force is applied to pusher 1200 to push implant1000 a desired amount into proximal portion 41 of disc space D1.Inserter 1100 is pivoted in the direction of arrow R, thereby pivotingleading end 1106 in the disc in the posterior direction. Pusher 1200,pivoted along with inserter 1200, is then used to apply a furtherimpaction force to push implant 1000 further into the disc space.However, due to the pivoting of inserter 1100 and pusher 1200, thedirection of insertion is now oriented more towards distal portion 37 ofdisc space D1. This alternating pivotal and pushing movement of implant1000 is continued until implant 1000 is placed in the proper position indisc space D1.

Implant 1000 provides many further advantages. The shape and location ofthe bars, struts and walls positions the load bearing members at thestrong bony surfaces of the vertebral endplates to provide maximum loadsupport capacity and avoid implant subsidence into the vertebralendplates. The double convexity of the upper and lower bearing membersin combination with the boomerang shape provides an intimate fit in thedisc space and a profile that matches the concavity of the endplates,providing implant stability and promoting fusion. The openings andhollow interior maximize the volume available to receive bone growthmaterial and also maximize the contact surface area between the bonegrowth material and the adjacent bony structure. Implant 1000 can bemade from titanium, surgical grade stainless steel, or otherbio-compatible material using fabricating techniques known in the art.

Referring now to FIGS. 59–64, there is shown another embodiment implantaccording to the present invention. Implant 1400 is an interbody fusiondevice or cage that can be packed with bone growth material or otherknown substance and inserted into disc space D1 to promote bony fusionbetween adjacent vertebrae V1 and V2. Implant 1400 has a boomerang orbanana shape that is suited for insertion from a postero-lateral oruni-lateral approach into disc space D1, after the disc space D1 hasbeen accessed and prepared using the above described instruments andtechniques. Implant 1400 is insertable through opening 35 and pivotallymoved and impacted through disc space D1 into distal portion 37. It isalso contemplated that disc space D1 can be accessed and prepared forimplant insertion using any other known techniques and instruments andother approaches to the disc space, such as lateral, anterior orantero-lateral approaches, for insertion of implant 1400.

Implant 1400 includes a body having a leading end portion 1450, atrailing end portion 1452, and a middle portion 1454 therebetween. Aconcave posterior wall 1402 and an opposite convex anterior wall 1404extend along middle portion 1454, and also along at least part of thecorresponding side of leading end portion 1450 and trailing end portion1452. Implant 1400 further includes an arcuate leading end wall 1406extending along leading end portion 1450 between posterior wall 1402 andanterior wall 1404. Implant 1400 also includes an arcuate trailing endwall 1408 extending along trailing end portion 1452 between posteriorwall 1402 and anterior wall 1404. Implant 1400 further includes an upperbearing surface 1410 and a lower bearing surface 1412 extending betweenwalls 1402, 1404, 1406 and 1408.

Implant 1400 has a height H1′ at the medial portion of posterior wall1402 and a second height H2′ at the medial portion of anterior wall1404. Upper bearing surface 1410 and lower bearing surface 1412 have aslight convexity between the posterior and anterior walls 1402, 1404,and height H2′ is greater then H1′ in order to correspond to the anatomyof the vertebral endplates on each side of disc space D1. Leading endwall 1406 and trailing end wall 1408 each have a height H3′ that is lessthan H1′ and H2′, and upper bearing surface 1410 and lower bearingsurface 1412 have a slight convexity between leading end 1406 andtrailing end 1408 as best shown in FIGS. 61–64. This double convexitysubstantially matches the double concavity of the adjacent vertebralendplates. Furthermore, the difference in heights between the upper andlower bearing surfaces at the anterior and posterior walls can beprovided so as to establish lordosis when implant 1400 is inserted inthe disc space. In one specific application, implant 1400 can beinserted from a postero-lateral approach to restore and maintain spinallordosis.

Upper bearing surface 1410 can further be provided with a number offirst grooves 1414 a along anterior wall 1404 and second grooves 1414 balong leading and trailing end walls 1406, 1408. Lower bearing surface1412 can be provided with a number of grooves 1416 a along anterior wall1404 and second grooves 1416 b along leading and trailing end walls1406, 1408. Grooves 1414 a, 1414 b and 1416 a, 1416 b increasefrictional resistance between the adjacent vertebral endplate and thebearing surfaces 1410, 1412 to resist posterior and anterior migrationof implant 1400 in the disc space.

In order to provide avenues for bone growth through implant 1400, thewalls of implant 1400 form a number of chambers opening at upper bearingsurface 1410 and lower bearing surface 1412. In particular, leading endportion 1450 includes first chamber 1418 and trailing end portion 1452includes second chamber 1420. Middle portion 1454 includes a middlechamber 1422. A first strut 1424 is located between first chamber 1418and third chamber 1422 and extends between posterior wall 1402 andanterior wall 1404. A second strut 1426 is located between secondchamber 1420 and third chamber 1422 and extends between posterior wall1402 and anterior wall 1404.

Posterior wall 1402 includes a posterior opening 1427 along middleportion 1454, and anterior wall 1404 includes an anterior opening 1428along middle portion 1454. In the illustrated embodiment, posterior wallopening 1427 is circular and anterior wall opening 1428 is oval orracetrack shaped and elongated in the direction between upper bearingsurface 1410 and lower bearing surface 1412; however, other shapes foropenings 1427, 1428 are also contemplated. Leading end portion 1450includes first and second wall openings 1430 a, 1430 b in anterior wall1404, and trailing end portion 1452 includes first and second wallopenings 1432 a, 1432 b in anterior wall 1404. In the illustratedembodiment, openings 1430 a, 1430 b and 1432 a, 1432 b are oval orracetrack shaped and elongated in the direction between upper bearingsurface 1410 and lower bearing surface 1412; however, other shapes foropenings 1430 a, 1430 b and 1432 a, 1432 b are also contemplated.

Anterior wall 1404 includes an offset portion 1434 that is offsetanteriorly with respect to the remaining portions of anterior wall 1404extending from either side thereof. Anterior offset portion 1434provides additional support of the vertebrae and strength to the body ofimplant 1400. A number of radiographic markers 1438 can also be providedin implant 1400 to facilitate X-ray assessment of the locating andpositioning of implant 1400 in the patient's body. Such markers areparticularly useful for an implant 1400 made from radiolucent material.In the illustrated embodiment, markers 1438 are provided at the midlineof anterior wall 1404 at the anterior most point defined by offsetportion 1434. Markers 1438 are also provided at the posterior-mostpoints of trailing end wall 1408 and leading end wall 1406. Positioningmarkers 1438 at these locations provides an indication of the anteriorand posterior placement of implant 1400 in the disc space, and also anindication of the lateral placement of implant 1400 in the disc space.Alignment of the end wall markers 1438 in a lateral X-ray indicatesproper orientation of implant 1400 in the disc space in the A-Pdirection.

Implant 1400 includes a recessed area 1446 extending along leading endwall 1406 and a portion of anterior wall 1404. Implant 1400 alsoincludes a recessed area 1442 extending along trailing end wall 1408 anda portion of anterior wall 1404. Recessed areas 1442, 1446 are locatedin the respective wall portions mid-height between upper bearing surface1410 and lower bearing surface 1412. Recessed surfaces 1442, 1446 areconfigured to receive a portion of an implant insertion instrument andto facilitate grasping of the implant, as discussed further below.

The symmetrical shape of implant 1400 allows implant 1400 to be insertedinto disc space D1 from a unilateral approach taken on either side ofthe spinous process, and by grasping either of leading end portion 1450or trailing end portion 1452 with an insertion instrument. Implant 1400is provided with a first inserter instrument engaging receptacle 1448 attrailing end portion 1452 and a second inserter instrument engagingreceptacle 1444 at leading end portion 1450. Each of the engagingreceptacles 1444, 1448 are configured along with adjacent recessed area1442, 1446 for engagement with an implant inserter instrument, such asinserter instrument 1500 described below. Trailing end wall 1408 andleading end wall 1406 could also include a threaded hole for engagementwith an inserter, such as inserter 1100 described above. In theillustrated embodiment, engaging receptacles 1444, 1448 are in the formof grooves that extend between upper bearing surface 1410 and lowerbearing surface 1412. Each of the grooves is aligned with acorresponding one of the first strut 1424 and second strut 1426. Firststrut 1424 and second strut 1426 provide bearing support to resistapplication of forces applied to the implant wall by an insertioninstrument positioned in the respective engaging receptacle 1444, 1448.

Implant 1400 has an axis C1 extending through its center longitudinally.Axis C1 extends generally in the direction between the leading end andthe trailing end of implant 1400, and is equal distance from the mostposterior point on leading end wall 1406 and the most posterior point ontrailing end wall 1408. Leading end wall 1406 is offset to the posteriorside of axis C1, and trailing end wall 1408 is offset to the posteriorside of axis C1. The offset in the leading end and trailing ends ofimplant 1400 facilitates the controlled insertion of implant 1400 alongcurved insertion path P.

Referring now to FIGS. 65–69, there are shown instruments suited forinserting an implant through a postero-lateral opening in a spinal discspace. Inserter instrument 1500 provides the surgeon the ability tocontrol insertion of an implant into the spinal disc space from apostero-lateral approach. Inserter instrument 1500 facilitatespositioning of the implant in the disc space such that the implantextends across the disc space to provide bilateral support of theadjacent vertebrae. Inserter instrument 1500 also facilitatespositioning of the implant in the disc space along a non-linearinsertion path. Inserter instrument 1500 can also be used to positionmultiple implants at various locations in the disc space, and also forinsertion of one or more implants from other approaches to the discspace.

Inserter instrument 1500 includes a proximal portion 1501 pivotallycoupled to a distal portion 1512. Proximal portion 1501 extends alongaxis 1520 when in a first position, and is pivotal relative to distalportion 1512 as indicated by proximal portion 1501′ and axis 1520′.Proximal portion 1501 includes a handle 1502. Handle 1502 is coupled toan outer shaft 1504 extending distally from handle 1502. An inner shaft1506 is slidably received in outer shaft 1504. Inner shaft 1506 isspring biased distally with respect to handle 1502 to engage a distalportion 1512 of inserter instrument 1500. An actuator 1508 is positionedaround outer shaft 1504 and engaged to inner shaft 1506 with pin 1516extending through a slot 1514 in outer shaft 1504. For proximal portion1501′, inner shaft 1506 and spring 1508 are removed to show slot 1514′though which pin 1516 extends. Actuator 1508 is moved proximally from afirst engaged position to a disengaged position to push inner shaft 1506against spring 1508, disengaging inner shaft 1506 from distal portion1512 and allowing proximal portion 1501 to be pivoted to the positionindicated by proximal portion 1501′.

Distal portion 1512 includes a shaft engaging portion 1522 extendingalong an axis 1524. Distal portion 1512 further includes a distalimplant engaging portion 1526 and a lateral offset portion 1528extending between shaft engaging portion 1522 and implant engagingportion 1526. Distal portion 1512 also includes a notched portion 1530for engagement with a pusher instrument, such as pusher instrument 1580shown in FIG. 65 a.

Pusher instrument 1580 includes a handle 1582, a shaft 1584 extendingproximally from handle 1582, and an inserter instrument engaging portion1586 at a distal end of shaft 1584. In the illustrated embodiment,inserter instrument engaging portion 1586 is a forked prong sized to bepositioned around notched portion 1530 and to push against shaftengaging portion 1522.

As shown in FIG. 66, shaft engaging portion 1522 includes a firstreceptacle 1522 a and a second receptacle 1522 b. Shaft engaging portion1522 further includes a through-hole 1522 e to receive a pin topivotally couple outer shaft 1504 thereto. Extending from firstreceptacle 1522 a on one side of hole 1522 e is a first surface 1522 c,and extending from second receptacle 1522 b on the other side of hole1522 e is a second surface 1522 d. Receptacles 1522 a and 1522 b areconfigured to receive first and second extensions 1506 a and 1506 b,respectively, extending distally from inner shaft 1506. In theillustrated embodiment, receptacles 1522 a, 1522 b are tapered tofacilitate sliding of extensions 1506 a, 1506 b therein between theirengaged and disengaged positions.

When proximal portion 1501 is in its first position, second extension1506 b extends along second surface 1522 d, and spring 1508 biases firstextension 1506 a into first receptacle 1522 a. First receptacle 1522 aengages first extension 1506 a such that proximal portion 1501 cannotpivot relative to distal portion 1512. When actuator 1508 is pulledproximally, first extension 1506 a is withdrawn proximally from firstreceptacle 1522 a sufficiently so that proximal portion 1501 can bepivoted relative to distal portion 1512 to the position indicated byproximal portion 1501′, wherein second extension 1506 b is aligned withsecond receptacle 1522 b. Actuator 1508 is released to spring biassecond extension 1506 b into second receptacle 1522 b, and firstextension 1506 a extends along first surface 1522 c. Second receptacle1522 b engages second extension 1506 b to prevent movement of proximalportion 1501′ relative to distal portion 1512 and lock proximal portion1501′ in the second position. Other embodiments contemplate that morethan two positions are provided for proximal portion 1501.

In FIG. 65 inserter instrument 1500 is positioned adjacent vertebra V1for insertion of an implant, such as implant 1400, into disc space D.When proximal portion 1501 is in its first position, as indicated byaxis 1520 in FIG. 66, axis 1524 of shaft engaging portion 1522 extendstoward vertebra V1 relative axis 1520. In the illustrated embodiment,axis 1524 forms angle B1 with axis 1520, and proximal portion 1501 ispivotal about an angle B2 between its first position indicated by axis1520 and its second position indicated by axis 1520′. Lateral offset1528 includes an axis 1529 that forms angle B3 with axis 1524, andimplant engaging portion 1526 has a distal portion with axis 1527forming angle B4 with lateral offset axis 1529. Implant 1400 has an axisC1 extending longitudinally therethrough that forms an angle B5 withdistal implant engaging portion axis 1527. When implant 1400 is insertedin disc space D, axis C1 can be oriented substantially orthogonally tothe sagittal plane of the spinal column.

In one specific embodiment, proximal portion 1501 moves between an angleB2 of 70 degrees between its first position along axis 1520 and itssecond position along axis 1520′. In this specific embodiment, shaftengaging portion 1522 extends from proximal portion 1501 at an angle B1of or about 135 degrees. Lateral offset 1528 extends along axis 1529forming an angle of or about 55 degrees. The distal portion of implantengaging portion 1526 extends along axis 1527 forming angle B4 of orabout 65 degrees with lateral offset portion 1528. Axis C1 of implant1400 forms an angle B5 of or about 65 degrees with axis 1527 of thedistal portion of implant engaging portion 1526. Other embodiments ofthe insertion instrument contemplate other values for angles B1, B2, B3,B4 and B5.

Implant engaging portion 1526 includes a first member 1532 and a secondmember 1534 movably engaged to first member 1532. Second member 1534 hasa first position along first member 1532, shown in FIG. 68, wherein aspinal implant such as implant 1400 is insertable between first andsecond members 1532, 1534. Second member 1534 is movable along firstmember 1532 to a second position wherein first member 1532 and secondmember 1534 engage implant 1400 therebetween.

First member 1532 includes a first arcuate finger 1532 a at a distal endthereof and second member 1534 includes a second arcuate finger 1534 aat a distal end thereof. With second member 1534 in its second position,first finger 1532 a and second finger 1534 a form an implant receptacle1536 sized and shaped to receive a trailing end wall of an implanttherein. In the illustrated embodiment, implant receptacle 1536 is sizedand shaped to conform to the trailing end wall 1408 of implant 1400.Other embodiments contemplate that implant receptacle 1536 is sized andshaped to conform to the trailing ends of other sized and shapedimplants.

Implant receptacle 1536 is defined by a first concave surface 1538extending along the inner side of first finger 1532 a of first member1532 and a second concave surface 1540 extending along the inner side ofsecond finger 1534 a of second member 1534. First concave surface 1538and second concave surface 1540 are oriented toward one another. Firstfinger 1532 a includes a projection 1541 extending from first concavesurface 1538 toward second concave surface 1540. Projection 1541 ispositionable in a hole or receptacle in implant 1400, such as hole 1432b. In the illustrated embodiment, first concave surface 1538 extendsalong the anterior wall of implant 1400, and second concave surface 1540extends along a portion of the posterior wall of implant 1400. Thecurvature of first concave surface 1538 can be greater than that ofsecond concave surface 1540 to accommodate the differences in curvatureof the respective wall portions of the implant against which concavesurfaces 1538, 1540 are positioned.

First finger 1532 a can be configured to reside at least partially inrecessed area 1442 extending along trailing end portion 1408 to minimizethe protrusion of first finger 1532 a into the adjacent anatomy and discspace during and after insertion of implant 1400. The height of finger1532 a can be less than the height of implant 1400 and correspond to theheight of recessed area 1442 so as to not contact the vertebralendplates during insertion and to facilitate detachment of engagingportion 1526 from implant 1400. Second finger 1534 a can have a heightthat is less than the height of implant 1400 so as to not contact thevertebral endplates during insertion and facilitate detachment ofengaging portion 1526 from implant 1400.

A driving member 1542 is provided to move second member 1534 between itsfirst and second positions. In the illustrated embodiment, drivingmember 1542 is in the form of an externally threaded cylindrical bodyrotatably captured in first member 1532. Driving member 1542 isthreadingly engaged to an internally threaded passage 1544 extendingalong second member 1534. Driving member 1542 is accessible throughopening 1546 for engagement with a driving tool (not shown.) In use,first finger 1532 a is positioned in recess 1442 with projection 1541 inhole 1432 b. The driving tool can be used to apply a force to rotatedriving member 1542 in a first direction to move second member 1534 viathreaded passage 1544. Second finger 1534 a is moved toward implant 1400until second finger 1534 a is firmly positioned in the groove formed atinserter instrument engaging receptacle 1448 of implant 1400, therebygripping implant 1400 in receptacle 1536 between fingers 1532 a, 1532 b.

There are further provided alignment instruments that extend fromproximal portion 1501 to point toward an anatomical feature of thepatient to provide an indication that the implant is properly positionedin disc space D. A first alignment instrument 1560 is removablyengageable to the proximal end of handle 1502. First alignmentinstrument 1560 includes a cup portion 1562 positionable over handle1502, and includes an extension member 1566 extending laterally to analignment member 1564. Extension member 1566 has a length between cupportion 1562 and alignment member 1564 sized for use with proximalportion 1501 in its first position. Alignment member 1564 extends towardthe patient and is alignable with an anatomical portion of the patientto provide an indication that the implant is properly positioned in discspace D. In the illustrated embodiment, alignment member 1564 alsoextends toward a reference point on implant 1400, such as the center ofimplant 1400 along its posterior and anterior walls. Thus, theanatomical feature to be aligned is positioned between the center ofimplant 1400 and the reference point on implant 1400. In the illustratedembodiment, alignment member 1564 aligns with or points to spinousprocess SP of vertebra V1 and also the center of implant 1400. Alignmentwith other anatomical features of the patient is also contemplated.

A second alignment instrument 1570 is removably engageable to proximalportion 1501 in its second position. Second alignment instrument 1570includes a cup portion 1572 positionable over handle 1502′, and includesan extension member 1576 extending laterally to an alignment member1574. Extension member 1576 has a length between cup portion 1572 andalignment member 1574 sized for use with proximal portion 1501′ in itssecond position. Alignment member 1574 extends toward the patient and isalignable with an anatomical portion of the patient, such as spinousprocess SP, and also a reference point on implant 1400, to provide anindication that the implant is properly positioned in disc space D.

One surgical procedure contemplated with inserter instrument 1500includes engaging an implant, such as implant 1400, to engaging portion1526. The disc space is accessed and prepared for postero-lateralinsertion of the implant. Proximal portion 1501 is engaged in its firstposition along axis 1520 relative to distal portion 1512. Inserterinstrument 1500 is positioned with respect to the entry to disc space Dsuch that leading end portion 1406 of implant 1400 is adjacent the discspace opening, and inserter instrument 1500 extends across the spinousprocess such as shown and discussed above with respect to instrument1100. Implant 1400 is inserted into disc space D by alternately and/orsimultaneously pivoting inserter instrument 1500 about the spinousprocess SP, as indicated by arrow R and pushing implant 1400 into discspace D, as indicated by arrow P. When implant 1400 is properlypositioned in disc space D, alignment instrument 1560 can be engaged, ifnot already so, to inserter instrument 1500. Orientation of alignmentmember 1564 toward spinous process SP provides an indication of properimplant positioning in disc space D. Insertion of implant 1400 and itspositioning in disc space D can also be confirmed radiographically orfluoroscopically. A pusher instrument, such as pusher instrument 1580,can be engaged with notched portion 1530 to assist in application of thepushing force to push implant 1400 across disc space D to the desiredposition.

It is further contemplated that proximal portion 1501 can be pivoted tothe position indicated by proximal portion 1501′ and axis 1520′.Movement of proximal portion 1501 from the first position to the secondposition can be completed when implant 1400 is partially inserted, orprior to insertion of implant 1400. It is further contemplated thatproximal portion 1501 can be moved back and forth between the first andsecond positions during implant insertion. The second position ofproximal portion 1501′ of inserter instrument 1500 facilitatesapplication of a pushing force, with or without pushing instrument 1580,to push implant 1400 across disc space D to the desired position withinserter instrument 1500. When proximal portion 1501′ in its secondposition, alignment member 1574 of alignment instrument 1570 is orientedtoward spinous process SP to provide an indication of proper implantpositioning in disc space D.

Referring now to FIGS. 70 and 71, there is shown the proximal portion ofanother embodiment inserter instrument 1600 and alignment instrument1670. Except as otherwise discussed, inserter instrument 1600 can besubstantially identical to inserter instrument 1500 discussed above.Inserter instrument 1600 includes a proximal portion 1601 movablyengaged to a distal portion. Proximal portion 1601 includes a handle1602 having a bore 1609 extending therein from the proximal end face ofhandle 1602. Handle 1602 further includes a well 1603 formed therein inwhich a ball mechanism resides. The ball mechanism includes a spring1605 and a ball 1607 movably captured in well 1603.

Alignment instrument 1670 includes an alignment member 1674 and anextension member 1676 such as discussed above with respect to alignmentinstruments 1560, 1570. The engagement end of alignment instrument 1670includes a rod portion 1672 positionable in bore 1603. Rod portion 1672includes a detent 1673 formed therein into which ball 1607 is removablyengaged to secure alignment instrument 1670 to inserter instrument 1600.It is contemplated that detent 1673 is positioned on rod portion 1672such that alignment instrument 1670 is properly aligned with the implantengaged to the implant engaging portion of insertion instrument 1600when ball 1607 is received in detent 1673.

FIG. 72 is an enlarged section view shown an alternate connectionarrangement between the proximal portion and the distal portion of theinserter instrument of FIG. 65. In FIG. 72 only a portion of proximalportion 1601 and distal portion 1612 are shown. Proximal portion 1601includes an outer shaft 1604 and an inner shaft 1606 movably receivedtherein. Outer shaft 1604 is pivotally engaged to distal portion 1612via a pin through pin hole 1622 d of implant engaging portion 1612. Anactuator (not shown) is coupled to inner shaft 1606 to move it in outershaft 1604 between an engaged position and a disengaged position withdistal portion 1612. Inner shaft 1606 is spring-biased distally andincludes a distal extension 1606 a for positioning in respective one ofa first receptacle 1622 a when proximal portion 1601 in its firstposition and a second receptacle 1622 b when proximal portion 1601 is inits second position. A pusher instrument notch 1630 and a lateralextension 1628 of distal portion 1612 are also shown, it beingunderstood these features and the remaining portion of distal portion1612 can be similar to or identical to that provided with distal portion1512 of inserter instrument 1500.

In the illustrated embodiment, extension 1606 a is rectangular and isreceived in close fitting engagement in respective ones of thereceptacles 1622 a, 1622 b to secure proximal portion 1601 in respectiveones of the first and second positions. Outer shaft 1604 includes adistal end surface 1604 a that is curved along an arc defined by thepivot path of proximal portion 1601. Distal end surface 1604 a movesalong a correspondingly curved proximal end surface 1622 c of distalportion 1612. Distal end surface 1604 a rides against proximal endsurface 1622 c to provide a firm coupling arrangement between proximalportion 1601 and distal portion 1612 during movement of proximal portion1601 and when proximal portion 1601 is in one of the first and secondpositions.

The implants described herein can be made from any biocompatiblematerial, including synthetic or natural autograft, allograft orxenograft tissues, and can be resorbable or non-resorbable nature.Examples of tissue materials include hard tissues, connective tissues,demineralized bone matrix and combinations thereof. Further examples ofresorbable materials are polylactide, polyglycolide, tyrosine-derivedpolycarbonate, polyanhydride, polyorthoester, polyphosphazene, calciumphosphate, hydroxyapatite, bioactive glass, and combinations thereof.Further examples of non-resorbable materials are non-reinforcedpolymers, carbon-reinforced polymer composites, PEEK and PEEKcomposites; shape-memory alloys; titanium and titanium alloys; cobaltchrome alloys; stainless steel; ceramics; and combinations thereof.Instruments described herein can be made from any suitable surgicalgrade material, including stainless steel, aluminum, plastics, andcombinations of materials.

Any suitable osteogenetic material or composition is contemplated forplacement within the chambers defined by the implants described herein.Such osteogenic material includes, for example, autograft, allograft,xenograft, demineralized bone, synthetic and natural bone graftsubstitutes, such as bioceramics and polymers, and osteoinductivefactors. Where bony material is placed within the chambers of theimplant, the material can be pre-packed into the hollow chambers beforethe device is implanted, or can be pushed through the wall openingsafter the device is in position in the spinal column. A separate carrierto hold the materials within the chambers of the device can also beused. These carriers can include collagen-based carriers, bioceramicmaterials, such as BIOGLASS®, hydroxyapatite and calcium phosphatecompositions. The carrier material can be provided in the form of asponge, a block, folded sheet, putty, paste, graft material or othersuitable form. Moreover, the osteogenetic compositions contained withinthe implant can comprise an effective amount of a bone morphogeneticprotein, transforming growth factor β1, insulin-like growth factor 1,platelet-derived growth factor, fibroblast growth factor, LIMmineralization protein (LMP), and combinations thereof or othertherapeutic or infection resistant agent, held within a suitable carriermaterial.

The above-described instruments and methods have been disclosed withreference to use in substantially open surgical procedures. However, itis contemplated that the implants, instruments and methods may beutilized through guide sleeves or tubes to provided greater protectionto adjacent tissues, to reduce the size of access incisions, to providedirect visualization of the surgical site, and/or to provide greatercontrol of the method. The implants, instruments and methods may furtherbe used in combination with disc space preparation and implant insertionthrough microscopic or endoscopic instruments that provide directvisualization of the surgical site, such as disclosed in U.S. patentapplication Ser. No. 09/692,932 entitled METHODS AND INSTRUMENTS FORENDOSCOPIC INTERBODY SURGICAL TECHNIQUES, filed Oct. 20, 2000, which isincorporated herein by reference in its entirety.

The instruments and methods have been disclosed with reference to aparticular application for disc space preparation and implant insertionfrom a transforaminal approach to the spine. However, there are aspectsof the inventions described herein that may be utilized or modified foruse for a variety of surgical applications including, but not limitedto, spinal surgery from a unilateral posterior approach, a lateralapproach, an oblique approach, and through laparoscopic or endoscopicinstruments from any of a variety of angles or approaches to the spine.

While the invention has been illustrated and described in detail in thedrawings and the foregoing description, the same is considered to beillustrative and not restrictive in character. It is understood thatonly the preferred embodiments have been shown and described and thatall changes and modifications that come within the spirit of theinvention are desired to be protected.

1. A spinal implant insertable in a spinal disc space, the implantcomprising a body including: a middle portion having opposite first andsecond ends and a convexly curved anterior wall and a concavely curvedposterior wall extending therebetween; a leading end portion extendingfrom said first end of said middle portion; a trailing end portionextending from said second end of said middle portion; an upper surfaceand an opposite lower surface along said middle portion and said leadingend portion and said trailing end portion; and an inserter instrumentengaging receptacle formed as a groove extending in a concavely curvedprofile extending along a junction of said middle portion and saidtrailing end portion.
 2. The implant of claim 1, wherein said grooveextends between said upper surface and said lower surface.
 3. Theimplant of claim 1, further comprising an inserter instrument engagingreceptacle at a junction of said middle portion and said leading endportion.
 4. The implant of claim 1, wherein said anterior wall and saidposterior wall each extend along a respective side of said middleportion, said leading end portion and said trailing end portion.
 5. Theimplant of claim 4, wherein said anterior wall has a generally convexprofile and said posterior wall has a generally concave profile.
 6. Theimplant of claim 4, wherein said anterior wall includes a recessed areaextending along said trailing end portion.
 7. The implant of claim 6,wherein said anterior wall includes a second recessed area extendingalong said leading end portion.
 8. The implant of claim 4, wherein saidposterior wall has a height that is less than a height of said anteriorwall.
 9. The implant of claim 1, wherein said leading end portion andsaid trailing end portion each define a chamber extending between saidupper surface and said lower surface.
 10. The implant of claim 9,wherein said middle portion defines a chamber extending between saidupper surface and said lower surface.
 11. The implant of claim 10,further comprising: a first strut between said chamber of said leadingend portion and said chamber of said middle portion; and a second strutbetween said chamber of said trailing end portion and said chamber ofsaid middle portion.
 12. The implant of claim 11, wherein said inserterinstrument engaging receptacle is formed at the junction of said secondstrut and a posterior wall of said body.
 13. The implant of claim 1,wherein said body is comprised of non-resorbable material selected fromthe group consisting of: non-reinforced polymers, carbon-reinforcedpolymer composites, PEEK, PEEK composites, shape-memory alloys,titanium, titanium alloys, cobalt chrome alloys, stainless steel,ceramics and combinations thereof.
 14. The implant of claim 1, whereinsaid body is comprised of PEEK material.
 15. The implant of claim 14,further comprising at least one radiographic marker in said body. 16.The implant of claim 1, wherein said body includes at least one chamber.17. The implant of claim 16, further comprising bone growth material insaid at least one chamber.
 18. The implant of claim 17, wherein saidbone growth material includes one or more selected from group consistingof: bone morphogenetic protein, transforming growth factor, insulin-likegrowth factor, platelet-derived growth factor, fibroblast growth factor,and LIM mineralization protein (LMP).
 19. A spinal implant insertable ina spinal disc space, the implant comprising a body having: a leading endwall; a trailing end wall; a concavely curved posterior wall extendingbetween said leading end wall and said trailing end wall; and a convexlycurved anterior wall extending between said leading end wall and saidtrailing end wall, wherein said anterior wall includes a middle portion,a trailing end portion, and a leading end portion, said middle portionincluding an offset portion projecting anteriorly from said middleportion of said anterior wall, wherein said middle portion includes anupper bearing surface and an opposite lower bearing surface extendingalong said anterior wall and said offset portion.
 20. The implant ofclaim 19, further comprising: said upper bearing surface extendingbetween said leading end wall, said anterior wall, said posterior walland said trailing end wall; and said opposite lower bearing surfaceextending between said leading end wall, said anterior wall, saidposterior wall and said trailing end wall.
 21. The implant of claim 19,wherein: said posterior wall includes a middle portion, a leading endportion, and a Wailing end portion; and said posterior wall includes aninserter instrument engaging receptacle at a junction of said middleportion and said trailing end portion thereof.
 22. The implant of claim21, wherein said receptacle is a groove extending between said uppersurface and said lower surface.
 23. The implant of claim 21, whereinsaid posterior wall includes an inserter instrument engaging receptacleat a junction of said middle portion and said leading end portionthereof.
 24. The implant of claim 19, wherein said anterior wall has agenerally convex profile and said posterior wall has a generally concaveprofile.
 25. The implant of claim 19, wherein said anterior wallincludes a first recessed area extending along said leading end portionthereof and a second recessed area extending along said trailing endportion thereof.
 26. The implant of claim 19, wherein said posteriorwall has a height that is less than a height of said anterior end wall.27. The implant of claim 19, further comprising a first chamber betweena leading end portion of said posterior wall and said leading endportion of said anterior wall and a second chamber between a trailingend portion of said posterior wall and said trailing end portion of saidanterior wall.
 28. The implant of claim 27, further comprising a thirdchamber between a middle portion of said posterior wall and said middleportion of said anterior wall.
 29. The implant of claim 28, furthercomprising: a first strut extending from said anterior wall to saidposterior wall between said first chamber and said third chamber; and asecond strut extending from said anterior wall to said posterior wallbetween said second chamber and said third chamber.
 30. The implant ofclaim 29, further comprising an inserter instrument engaging receptaclein said posterior wall at the junction of said second strut and saidposterior wall.
 31. The implant of claim 30, further comprising a secondinserter instrument engaging receptacle in said posterior wall formed atthe junction of said first strut and said posterior wall.
 32. A spinalimplant insertable in a spinal disc space, the implant comprising a bodyincluding: a leading end wall; a trailing end wall; a posterior wallextending between said leading end wall and said trailing end wall; ananterior wall extending between said leading end wall and said trailingend wall; a first strut adjacent said leading end wall extending fromsaid anterior wall to said posterior wall; a second strut adjacent saidtrailing end wall extending from said anterior wall to said posteriorwall; a chamber formed by said first strut, said second strut, saidanterior wall and said posterior wall; and an inserter instrumentengaging receptacle at the junction of said second strut and saidposterior wall.
 33. The implant of claim 32, further comprising: asecond chamber formed by said first strut, said leading end wall, saidanterior wall and said posterior wall; and a third chamber formed bysaid second strut, said trailing end wall, said anterior wall and saidposterior wall forming a second chamber.
 34. The implant of claim 32,wherein said anterior wall includes a middle portion, a trailing endportion, and a leading end portion, said middle portion being offsetanteriorly from said leading end portion and said trailing end portion.35. The implant of claim 32, further comprising an inserter instrumentengaging receptacle at the junction of said first strut and saidposterior wall.
 36. A spinal implant insertable in a spinal disc space,the implant comprising a body including: a middle portion havingopposite first and second ends; a leading end portion extending fromsaid first end of said middle portion; a trailing end portion extendingfrom said second end of said middle portion; an upper surface and anopposite lower surface along said middle portion and said leading endportion and said trailing end portion; and an inserter instrumentengaging receptacle at a junction of said middle portion and saidtrailing end portion, wherein said receptacle is a groove formed in aposterior wall of said body, said groove extending between said uppersin-face and said lower surface.
 37. The implant of claim 36, furthercomprising an inserter instrument engaging receptacle at a junction ofsaid middle portion and said leading end portion.
 38. The implant ofclaim 36, wherein said body includes an anterior wall and a posteriorwall each extending along a respective side of said middle portion, saidleading end portion and said trailing end portion.
 39. The implant ofclaim 38, wherein said anterior wall has a generally convex profile andsaid posterior wall has a generally concave profile.
 40. The implant ofclaim 38, wherein said anterior wall includes a recessed area extendingalong said trailing end portion.
 41. The implant of claim 40, whereinsaid anterior wall includes a second recessed area extending along saidleading end portion.
 42. The implant of claim 38, wherein said posteriorwall has a height that is less than a height of said anterior end wall.43. The implant of claim 36, wherein said leading end portion and saidtrailing end portion each define a chamber extending between said uppersurface and said lower surface.
 44. The implant of claim 43, whereinsaid middle portion defines a chamber extending between said uppersurface and said lower surface.
 45. The implant of claim 44, furthercomprising: a first strut between said chamber of said leading endportion and said chamber of said middle portion; and a second strutbetween said chamber of said trailing end portion and said chamber ofsaid middle portion.
 46. The implant of claim 45, wherein said inserterinstrument engaging receptacle is formed at the junction of said secondstrut and a posterior wall of said body.
 47. The implant of 36, furthercomprising bone growth material in a chamber of said body, wherein saidbone growth material includes one or more selected from group consistingof: bone morphogenetic protein, transforming growth factor, insulin-likegrowth factor, platelet-derived growth factor, fibroblast growth factor,and LIM mineralization protein (LMP).
 48. A spinal implant insertable ina spinal disc space, the implant comprising a body including: a middleportion having opposite first and second ends; a leading end portionextending from said first end of said middle portion; a trailing endportion extending from said second end of said middle portion; an uppersurface and an opposite lower surface along said middle portion and saidleading end portion and said trailing end portion; and an inserterinstrument engaging receptacle at a junction of said middle portion andsaid trailing end portion, wherein said body includes an anterior walland a posterior wall each extending along a respective side of saidmiddle portion, said leading end portion and said trailing end portion,said anterior wall has a generally convex profile, and said posteriorwall has a generally concave profile and includes said inserterinstrument engaging receptacle in said concave profile.
 49. The implantof claim 48, wherein said receptacle is a groove extending between saidupper surface and said lower surface.
 50. The implant of claim 48,further comprising an inserter instrument engaging receptacle at ajunction of said middle portion and said leading end portion.
 51. Theimplant of claim 48, wherein said anterior wall includes a recessed areaextending along said trailing end portion.
 52. The implant of claim 51,wherein said anterior wall includes a second recessed area extendingalong said leading end portion.
 53. The implant of claim 48, whereinsaid posterior wall has a height that is less than a height of saidanterior end wall.
 54. The implant of claim 48, wherein said leading endportion and said trailing end portion each define a chamber extendingbetween said upper surface and said lower surface.
 55. The implant ofclaim 54, wherein said middle portion defines a chamber extendingbetween said upper surface and said lower surface.
 56. The implant ofclaim 55, further comprising: a first strut between said chamber of saidleading end portion and said chamber of said middle portion; and asecond strut between said chamber of said trailing end portion and saidchamber of said middle portion.
 57. The implant of claim 56, whereinsaid inserter instrument engaging receptacle is formed at the junctionof said second strut and a posterior wall of said body.
 58. The implantof 48, further comprising bone growth material in a chamber of saidbody, wherein said bone growth material includes one or more selectedfrom group consisting of: bone morphogenetic protein, transforminggrowth factor, insulin-like growth factor, platelet-derived growthfactor, fibroblast growth factor, and LIM mineralization protein (LMP).59. A spinal implant insertable in a spinal disc space, the implantcomprising a body including: a middle portion having opposite first andsecond ends; a leading end portion extending from said first end of saidmiddle portion; a trailing end portion extending from said second end ofsaid middle portion; an upper surface and an opposite Iowa surface alongsaid middle portion and said leading end portion and said trailing endportion; and an inserter instrument engaging receptacle at a junction ofsaid middle portion and said trailing end portion, wherein said bodyincludes an anterior wall and a posterior wall each extending along arespective side of said middle portion, said leading end portion andsaid trailing end portion and said anterior wall includes a recessedarea extending along said trailing end portion from said receptacle, andfurther comprising: a first strut between said chamber of said leadingend portion and said chamber of said middle portion; and a second strutbetween said chamber of said trailing end portion and said chamber ofsaid middle portion.
 60. The implant of claim 59, wherein saidreceptacle is a groove formed in a posterior wall of said body, saidgroove extending between said upper surface and said lower surface. 61.The implant of claim 59, wherein said anterior wall has a generallyconvex profile and said posterior wall has a generally concave profile.62. The implant of claim 59, wherein said anterior wall includes asecond recessed area extending along said leading end portion.
 63. Theimplant of claim 59, wherein said posterior wall has a height that isless than a height of said anterior end wall.
 64. The implant of claim59, wherein said leading end portion and said trailing end portion eachdefine a chamber extending between said upper surface and said lowersurface.
 65. The implant of claim 64, wherein said middle portiondefines a chamber extending between said upper surface and said lowersurface.
 66. The implant of claim 59, wherein said inserter instrumentengaging receptacle is formed at the junction of said second strut and aposterior wall of said body.
 67. The implant of 59, further comprisingbone growth material in a chamber of said body, wherein said bone growthmaterial includes one or more selected from group consisting of: bonemorphogenetic protein, transforming growth factor, insulin-like growthfactor, platelet-derived growth factor, fibroblast growth factor, andLIM mineralization protein (LMP).
 68. A spinal implant insertable in aspinal disc space, the implant comprising a body including: a middleportion having opposite first and second ends and having a convexlycurved anterior wall and concavely curved posterior wall; a leading endportion extending from said first end of said middle portion; a trailingend portion extending from said second end of said middle portion; anupper surface and an opposite lower surface along said middle portionand said leading end portion and said trailing end portion; and aninserter instrument engaging receptacle at a junction of said middleportion and said trailing end portion in a concavely curved profilealong said middle portion and said trailing end portion, wherein saidposterior wall has a height that is less than a height of said anteriorwall.
 69. The implant of claim 68, wherein said receptacle extendsbetween said upper surface and said lower surface.
 70. The implant ofclaim 68, wherein said anterior wall includes an offset portion forminga change in profile of said anterior wall along said middle portion. 71.The implant of claim 68, wherein said leading end portion and saidtrailing end portion each define a chamber extending between said uppersurface and said lower surface.
 72. The implant of claim 71, whereinsaid middle portion defines a chamber extending between said uppersurface and said Lower surface.
 73. The implant of claim 72, furthercomprising: a first strut between said chamber of said leading endportion and said chamber of said middle portion; and a second strutbetween said chamber of said trailing end portion and said chamber ofsaid middle portion.
 74. The implant of claim 73, wherein said inserterinstrument engaging receptacle is formed at the junction of said secondstrut and a posterior wall of said body.
 75. A spinal implant insertablein a spinal disc space, the implant comprising a body having: a leadingend wall; a trailing end wall; a posterior wall extending between saidleading end wall and said trailing end wall; and an anterior wallextending between said leading end wall and said trailing end wall,wherein said anterior wall includes a middle portion, a trailing endportion, and a leading end portion, said middle portion being offsetanteriorly from said leading end portion and said trailing end portion,wherein: said posterior wall includes a middle portion, a leading endportion, and a trailing end portion; said posterior wall includes aninserter instrument engaging receptacle at a junction of said middleportion and said trailing end portion thereof: and said middle portionoffset forms an abrupt change in profile of said anterior wall.
 76. Theimplant of claim 75, further comprising: an upper bearing surfaceextending between said leading end wall, said anterior wall, saidposterior wall and said trailing end wall; and an apposite lower bearingsurface extending between said leading end wall, said anterior wall,said posterior wall and said trailing end wall.
 77. The implant of claim75, wherein said receptacle is a groove extending said upper surface andsaid lower surface.
 78. The implant of claim 77, wherein said posteriorwall includes an inserter instrument engaging receptacle at a junctionof said middle portion and said leading end portion thereof.
 79. Theimplant of claim 75, wherein said anterior wall has a generally convexprofile and said posterior wall has a generally concave profile.
 80. Theimplant of claim 75, wherein said anterior wall includes a firstrecessed area extending along said leading end portion thereof and asecond recessed area extending along said trailing end portion thereof.81. The implant of claim 75, further comprising a first chamber betweena leading end portion of said posterior wall and said leading endportion of said anterior wall and a second chamber between a trailingend portion of said posterior wall and said trailing end portion of saidanterior wall.
 82. The implant of claim 81, further comprising a thirdchamber between a middle portion of said posterior wall and said middleportion of said anterior wall.
 83. The implant of claim 82, furthercomprising: a first strut extending from said anterior wall to saidposterior wall between said first chamber and said third chamber; and asecond strut extending from said anterior wall to said posterior wallbetween said second chamber and said third chamber.
 84. The implant ofclaim 83, further comprising an inserter instrument engaging receptaclein said posterior wall at the junction of said second strut and saidposterior wall.
 85. The implant of claim 84, further comprising a secondinserter instrument engaging receptacle in said posterior wall formed atthe junction of said first strut and said posterior wall.
 86. A spinalimplant insertable in a spinal disc space, the implant comprising a bodyhaving: a leading end wall; a trailing end wall; a posterior wallextending between said leading end wall and said trailing end wall; andan anterior wall extending between said leading end wall and saidtrailing end wall, wherein said anterior wall includes a middle portion,a trailing end portion, and a leading end portion, said middle portionbeing offset anteriorly from said leading end portion and said trailingend portion, wherein said anterior wall includes a first elongatedcontinuous recess extending along said leading end portion thereof and asecond elongated continuous recess extending along said trailing endportion thereof.
 87. The implant of claim 86, further comprising: anupper bearing surface extending between said leading end wall, saidanterior wall, said posterior wall and said trailing end wall; and anopposite lower bearing surface extending between said leading end wall,said anterior wall, said posterior wall and said trailing end wall. 88.The implant of claim 86, wherein: said posterior wall includes a middleportion, a leading end portion, and a trailing end portion; and saidposterior wall includes an inserter instrument engaging receptacle at ajunction of said middle portion and said trailing end portion thereof.89. The implant of claim 88, wherein said receptacle is a grooveextending said upper surface and said lower surface.
 90. The implant ofclaim 88, wherein said posterior wall includes an inserter instrumentengaging receptacle at a junction of said middle portion and saidleading end portion thereof.
 91. The implant of claim 86, wherein saidanterior wall has a generally convex profile and said posterior wall hasa generally concave profile.
 92. The implant of claim 86, wherein saidposterior wall has a height that is less than a height of said anteriorwall.
 93. The implant of claim 86, further comprising a first chamberbetween a leading end portion of said posterior wall and said leadingend portion of said anterior wall and a second chamber between atrailing end portion of said posterior wall and said trailing endportion of said anterior wall.
 94. The implant of claim 93, furthercomprising a third chamber between a middle portion of said posteriorwall and said middle portion of said anterior wall.
 95. The implant ofclaim 94, further comprising: a first strut extending from said anteriorwall to said posterior wall between said first chamber and said thirdchamber; and a second strut extending from said anterior wall to saidposterior wall between said second chamber and said third chamber. 96.The implant of claim 95, further comprising an inserter instrumentengaging receptacle in said posterior wall at the junction of saidsecond strut and said posterior wall.
 97. The implant of claim 96,further comprising a second inserter instrument engaging receptacle insaid posterior wall formed at the junction of said first strut and saidposterior wall.